FT8 Operating Guide

Weak signal HF DXing for technophiles

by Gary Hinson ZL2iFB Version 2.37

Note: this document is occasionally updated . The definitive latest English version is

maintained at https://www.g4ifb.com/FT8_Hinson_tips_for_HF_DXers.pdf Please

use and share that URL or the shortcut bit.ly/FT8OP to stay current. Any archived

copies, translations and extracts lurking elsewhere on the Web are not under my

control and are probably out of date … but it’s possible they are even better than this

version!

FT8 Operating Guide

By Gary Hinson ZL2iFB

Introduction and purpose of this document ............................................................................... 2

START HERE............................................................................................................................... 3

Important: accurate timing ........................................................................................................ 5

Important: transmit levels ......................................................................................................... 8

Important: receive levels ......................................................................................................... 11

Other software settings ........................................................................................................... 14

How to respond to a CQ, or call a specific station ..................................................................... 17

How to call CQ......................................................................................................................... 24

Logging digimode QSOs............................................................................................................ 28

0 Hinson tips: miscellaneous FT8 operating tips .......................................................................... 30

1 Special callsigns ....................................................................................................................... 50

2 DXpeditioning with FT8............................................................................................................ 54

3 Flaws, bugs and improvements ................................................................................................ 59

4 Close and acknowledgements .................................................................................................. 62

Appendix A: About FT8 ................................................................................................................... 63

Appendix B: JS8 for weak signal text chat........................................................................................ 64

Appendix C: JTDX............................................................................................................................ 65

Appendix D: FT8 under the hood..................................................................................................... 71

Appendix E: FT8 logging and lookups .............................................................................................. 74

Appendix F: Contesting with WSJT-X............................................................................................... 76

Appendix G: Picking FT8 cherries with Logger32.............................................................................. 78

Appendix H: FT4, a digimode for contesting .................................................................................... 82

Recent changes to this document (just the

stuff)

Version

Date

Changes made

2

.37

.36

.35

Sept 2021 New chapter about logging (tnx for the inspiration Joe W4JF).

June 2021 Tips on working a fox (tnx Ned AA7A ).

Mar 2021 Noted JTsync (thanks Gust ON6KE). New front graphic, courtesy of Club Log .

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FT8 Operating Guide

1

Introduction and purpose of this document

1

.1

I started compiling these notes back in July 2017 in the

course of making over 50,000 FT8 QSOs on the HF bands,

learning how to drive the software by using it. Some tips

were inspired by suggestions from other FT8 users and by

the WSJT-X developers on the WSJT-X reflector (worth

joining). Many address Frequently Asked Questions and

draw on my 40-odd years of HF DXing … some very odd.

Some of my tips (such as split

operating, tail-ending and using

low power) are contentious and

not universally adopted by FT8

users – and that’s fine. To an

extent, we are figuring this stuff

out for ourselves as we go along,

which for me is all part of the fun.

These tips work for me. Your

situation and preferences may

.2

.3

That said, these are just tips, pragmatic suggestions aimed

at making FT8 easier and more effective to use on the HF

bands. They are not rules or laws! It’s only a hobby! The

digital modes, protocols and programs are being actively

developed, while the operating conventions or habits on-

air are still evolving. Other approaches may be even better me know if they work better. ꢀ

than those I suggest here … and that’s cool.

vary.

By all means try out

different approaches … and do let

In particular, I must point out that I am a keen HF

DXer with zero experience using FT8 intentionally

for meteor/rain/aircraft scatter, EME, topband and

VLF, 6m and up etc. I have only used FT8 on 80

through 10 metres. Hopefully much of the advice

here is useful in other contexts (e.g. topband

DXing) but different techniques may well be

appropriate and necessary, in which case please

I am primarily a Microsoft Windows

sufferer user. WSJT-X is an impressive

example of multi-platform coding that

works on Linux, MacOS, Windows (XP and

up) and other platforms, with only minor

differences … but since I only run it on

Windows 8.1, please don’t pelt me with

rotten tomatoes if things don’t quite work

look elsewhere for guidance. Likewise for other

modes such as JT9 and MSK144.

as described on your system.

RTFM! Seriously, please study the docs! The FT8 software installation instructions, online user guide ,

built-in help and tooltip popups will help you install, configure and start using the software with your

computer and rig. Most initial issues, problems and queries are answered therein, plus there are

useful tips. This “Operating Guide” is intended to help you get the best out of FT8 from an

operational perspective after you have it up and running. If you still have issues after all that, please

search the online support forum (reflector) archives … and finally feel free to ask for help on the

reflector. The developers are focused on designing, developing and refining the protocols so please

have some consideration: basic queries answered elsewhere are likely to remain unanswered.

Important disclaimer

We are all individually responsible and indeed accountable for complying with our

licenses plus applicable laws, regulations and conventions that may, for instance,

specify permitted powers, modes, bands/frequencies (e.g. on 60m) and bandwidths,

or impose obligations concerning remote operation, on-air identification and logging.

Just because the software allows us to do something does not necessarily mean it is

legal and appropriate for us to do so. Neither the development teams, nor the author

of this guide, are responsible for your compliance. You are, dear reader!

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FT8 Operating Guide

2

START HERE

2

.1

Use the latest available release of the FT8 software. You have a few program choices:

•

WSJT-X was written by the team that invented the mode (the daddies, you might say!). In the

best tradition of amateur radio, WSJT-X is open-source, hence others are developing variants

(

derivatives) of the program, changing the user interface and in some cases meddling with the

decoding and encoding under the covers.

JTDX by Igor UA3DJY and team is a stable, usable variant with several helpful tweaks to the user

interface. It is similar enough to be familiar to anyone who already knows WSJT-X. Although

sadly the official JTDX documentation is woefully out of date, see Appendix D for tips on using

JTDX and check out the JTDX YouTube video channel .

The user interface in MSHV by Christo LZ1HV is a little different. MSHV enables semi-rare DX

stations to make several QSOs in parallel using the regular FT8 protocol (not fox-n-hounds

DXpedition mode – more hunt saboteur mode) … at the cost of increased transmit bandwidth

(

higher band occupancy) and less power per signal. The multi-QSO facility does not work in

contest mode (thankfully!) and should not be used in the normal FT8 sub-bands, please.

•

JS8call by Jordan KN4CRD is a derivative that re-purposes the core FT8 digital transmission

protocol to enable longer free-text messages to be exchanged. This allows a more

conversational style of QSOs at the same leisurely rate of about 5 words per minute. As with

plain FT8 and in contrast to CW, RTTY and PSK, messages are sent blockwise as heavily-

compressed messages, not as individual characters. IT REMINDS ME OF TELEX <STOP> Or

Twitter. Or simplex traffic handling <OV ER>

Logging programs (such as Logger32 and N1MM+) can interface to FT8 programs, effectively

using them as intelligent soft modems. Maybe one day the loggers will take over the

sequencing, highlighting etc. leaving just the message coding and decoding to the modems, but

for now the programs interface to share tasks such as logging completed QSOs .

2

.2

Software updates are frequent with all variants as bugs

and flaws are discovered and fixed, and new functions

Aside from ‘alpha’, ‘beta’ and

production’ there are other,

roughly equivalent terms. WSJT-X

‘

are released for alpha or beta testing.

If

imperfect/incomplete software makes your blood boil,

give FT8 a wide

has its ‘Release Candidates’ and

‘

General Availability’ versions. JTDX

It’s worth checking from time

to time for new versions of the

berth and keep your

cool. If you prefer

uses ‘Evaluation versions’, ‘Step

releases’ and ‘General releases’.

software and this guide . Make

reasonably stable

it part of your routine e.g. at

and reliable software, stick with the production releases,

avoiding the betas and definitely the alphas.

the start of the month, and/or

keep an eye on social media.

Read the WSJT-X v2.4 User Guide .

Please, read it. Study it. Ingest it. Memorize it.

Banish dumb questions! Be like FT8 boss!

This advice stands even if you use JTDX.

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FT8 Operating Guide

2

.3

.4

With your chosen software running, press F1 and study the help file/manual. The WSJT-X help is

well written, if I say so myself. You’ll discover, for instance, that the confusing combinations of

shift, alt or control keys and clicks are handily explained on the screen by pressing F5 to “Display

special mouse commands”. By far the most useful combination in WSJT-X is to shift-click on the

waterfall to put your transmitted signal there (think of it as ‘shift my Tx ’). If nothing else sticks

from these notes, at least remember to shift-click … or right click in JTDX .

Although not yet shown on the pop-up help, we can also right-click on the WSJT-X waterfall and

1

then click the only option to set both Rx and Tx frequencies right there .

From time to time, check for

updates to the digimode software,

as you should for all the other

software on your system. Most

applications, operating systems

and drivers are updated or

patched occasionally, addressing

bugs and flaws or adding new

facilities (potentially including

changes to the FT8 protocol itself).

WSJT-X does not automate this for

us but it’s not hard to check the

website .

New releases are

announced on the WSJT-X

reflector and the news soon

percolates through other ham

radio forums, plus on-air of course.

It’s much the same with JTDX and

MSHV : join the online communities or monitor the authors’ websites to keep up with

developments.

1

Why we can’t simply left-click to move the Rx and right-click to move the Tx in WSJT-X is beyond me. Much more intuitive …

and that approach works perfectly well in JTDX .

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FT8 Operating Guide

3

Important: accurate timing

3

.1

Check your computer’s clock. Accurate timing is quite

important for FT8: if your computer clock is wrong by more

than a second or so, you will probably experience problems

e.g. few responses to your CQs and being ignored whenever

you call others.

If you see plenty of FT8

signals on the waterfall but

few decodes, blobs that cross

the horizontal tramlines on

the waterfall and/or a distinct

bias in the DT values on the

decode, those are all strong

clues that your computer’s

clock may need resetting.

Note: despite what some may claim, extreme millisecond

accuracy is NOT required. FT8 signals contain distinctive

synchronisation sequences that the receiving systems use to

identify the data portions in the received audio stream.

Accuracy to within a second is plenty good enough in practice.

If your computer is Internet-connected, it’s easy to check the clock by browsing to the Time.is

website . If your clock is accurate, you should see something like this ▼

3

.2

JTDX displays a rolling average of the DT values (delta time i.e. how many seconds each message

is offset relative to the expected start and finish times according to the system clock) and two Lag

values (i.e. how many seconds into

the start of the next period it took

your computer to decode the

messages shown, followed by the

count of messages decoded) in

Band Activity header area (if wide

enough) ►

On a busy band, if everyone else seems to be a bit early or late, chances are that your own clock is

wrong. An average DT value between minus 1 and plus 1 is fine in practice since JTDX can still

decode reliably even with DT of 2 seconds (e.g. if a DX station’s clock is a second fast while your

clock is running a second slow). If your average DT is more than ±1, adjust your clock.

The Lag values indicate whether your computer has enough processing power. QRP computers

struggle to decode all the messages on a busy band, especially if you have configured the software

to dig deep into the noise for every last scrap of information. Conversely, QRO computers cope

easily and quickly with all the signal processing required, without intruding very far (if at all) into

the next period. So, if you see large lags and often notice late decodes appearing after you have

started transmitting a message, it may be time to fiddle with the software settings, close down

other programs to conserve resources for FT8, or consider upgrading your trusty old difference

engine or steam-powered abacus to something more modern, more this-century.

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FT8 Operating Guide

3

.3

Manually adjusting your system clock soon becomes annoying, trust me. There are better ways.

For starters, pop open the computer lid and check/replace the button-cell battery that should keep

the real time clock running even when the PC is powered down. Provided you have Internet access,

the free Meinberg NTP software maintains clock accuracy, initially by synchronising your PC time

to reference time servers on the Internet using N etwork T ime P rotocol designed for that purpose,

and then micro-adjusting the clock’s tick rate to remain synchronised (rather than just periodically

resetting the clock, which is the more common but cruder approach). Install, configure , check,

forget: it’s that easy with Meinberg NTP. If Meinberg do esn’t suit you, there are several

alternatives such as BktTimeSynch by IZ2BKT , Dimension 4, TimeSynchTool, JTSync and many

others , each with their fans.

3

.4

Recent versions of Windows Server and Windows 10 offer an updated W32Time time service called

accurate time with markedly better timing capabilities, claimed millisecond accuracy (under

defined conditions ) and lots of configuration parameters and registry settings . It can be started,

stopped, configured and queried from an elevated command prompt e.g.

C:\> w32tm /config /update /manualpeerlist:pool.ntp.org,0x1

…

•

where:

/config means we are reconfiguring the W32tm Windows time service

/update means apply the config changes to the service

•

/manualpeerlist: means we want to specify NTP time servers other than the Windows default

server time.windows.com

•

pool.ntp.org tells the system to choose a nearby time server from the global pool. There are

several regional pools (e.g. oceania.pool.ntp.org) and country pools (e.g. nz.pool.ntp.org) or

you can name one or more specific time servers instead (separate their addresses with commas)

,0x1 is a flag meaning use the ‘special poll interval’ for this server, where ‘special poll interval’

is a fixed value in seconds defined in the registry under this key:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpClient

e.g. a SpecialPollInterval of 600 decimal means poll the time server every 10 minutes.

If you are unconcerned about the accuracy of your clock but simply want to work

someone with timing issues, you can deliberately nudge your clock forward or

backward manually. You may notice their blobs don’t line up with the horizontal

timing lines on the waterfall, as in this example ► YD3BGM’s messages were decoded

OK ▼ with an uncorrected DT of -2.4 seconds (i.e. he was transmitting 2.4 seconds

early, relative to my computer

clock). On the headphones, I

heard his tones starting well

before other stations using

the same timeslots. First I

called him several times without success,

despite the path being wide open between

us.

P a g e |6

FT8 Operating Guide

Guessing that he might be using software with less tolerance on timing, I

clicked to open the Windows system clock ► opened the change date

and time settings function, clicked the Change date and time button,

clicked the seconds part of the digital clock, clicked the up arrow 2 or 3

times to advance my clock by about 2 or 3 seconds (deliberately making

my system clock inaccurate!), then clicked OK to set the clock. After

checking the decodes to confirm that his DT was reduced to just 0.2

seconds, I responded to his CQ call again and this time we completed a

QSO easily. I closed with a free-text message “CHK UR CLOCK” … which

he evidently did a few minutes later. Meanwhile I had reset my own

system clock until the time.is website showed it was within a second of the

correct time. Meinberg NTP (which I simply left running throughout the

process) adjusts the clock rate to correct it gradually from there and

maintains millisecond accuracy until the next time I run into the same

situation.

Tip: to move his

blobs up the

waterfall, click

the up arrow.

3

.5

From time to time, the FTn reflectors suffer zombie

If you are offline (perhaps clinging

precariously to a mountain peak on a

SOTA expedition, or on a remote IOTA

DXpedition), you can use a GPS

receiver or radio time standards such

as WWV to check and adjust the

computer clock. Even a reasonably

accurate quartz watch will do provided

it was recently checked against a

reliable time reference before you set

out. Alternatively, simply listen to the

FT8 signals on a lively band to figure

out when most of them start and stop:

that’s your cue to set your clock.

outbreaks whenever someone naively asks what is the

best way to set their system time, or suggests some

other way to meddle with the time settings. GPS

pucks, Rasperry Pies, WWV, mean(DT), clock-nudgers

and other such ideas have all come up, repeatedly,

been kicked around for a while before eventually

slipping back to the graveyard … until the next

outbreak. For all home-based hams, any suggestion

not involving a definitive time reference is

fundamentally unsound. Those involving atomic

clocks may be viable … but are generally trumped by

“

Use an NTP time server from the pool” if you are

Internet-connected, or “Use GPS” if not. How to do

that is simply a matter of personal choice. There is

plenty of advice on the web already.

[

Thanks Rod YJ8RN for the tip]

“

These modes are not designed for long conversations or ragchewing. Rather

they concentrate on efficient exchange of such basic information as call signs,

Maidenhead grid locators, signal reports, and acknowledgements at the

lowest possible signal-to-nois e ratios, in the space of a few minutes or less.”

“

Work the World with WSJT-X, Part 1: Operating Capabilities ”

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FT8 Operating Guide

4

Important: transmit levels

4

.1

Although FT8 is a constant-carrier FSK

mode (unlike PSK, CW and SSB),

overdriving will distort and widen your

signal (making it less likely to decode)

and may generate spurii. Set the

transmit levels so that the entire chain

from AF generation through to RF

transmission is operating linearly.

Check out your transceiver, sound system and

software on-air on a quiet frequency with a

competent ham giving you honest feedback, or while

monitoring your own transmissions on a Web SDR as

you systematically adjust the settings and make

notes. Beware, though, that web SDRs can be

overloaded by strong signals, so don’t.

4

.2

If you set your transmit levels as badly as the FT8 station ringed in red on the left ▼ you may

unknowingly be generating ‘ghostly barcodes’ (in the 3 dotted rings): despite looking like some

obscure new digimode, these are audio harmonics caused by generating too much audio output

from the PC sound card which overloads the audio input circuits in the radio: [Tnx tip Bill G4WJS].

4

.3

.4

Setting your transmit levels is a bit more complicated than it seems: simply adjusting the rig’s

power output control is not sufficient as even QRP signals can be rotten if the rig’s audio is

overloaded and distorted.

Take care adjusting the audio output level from the sound

card and audio input level to the rig: consult your radio

manual to find out how to set the audio drive level

properly. On some rigs, the ALC meter is, in effect, a

distortion meter: any non-zero ALC indication is bad news.

On rigs that use ALC to control the power output

Sorry I can’t be more specific here.

If you are unsure, err on the side

of caution: keep your PC audio

output level low, just enough

drive to generate some RF output

(you don’t need much!).

(e.g. Icoms), high ALC indication is normal at QRP levels, so

it’s not much help for setting the audio input.

On the Elecraft K3, set the PC sound card

output (using the sound card headphone

level slider and/or the “Pwr” slider on the

WSJT-X/JTDX main window) and the K3’s line

input level (confusingly, using the front panel

“

MIC” control in DATA mode) to indicate 4

blobs on the ALC meter with a flickering fifth

blob indicating the onset of ALC action ►

Listen to your transmitted audio using the rig’s monitor function – maybe not all the

time but it pays to listen occasionally just in case, for some reason, you are

transmitting distorted audio, PC bleeps, DX announcements, wideband noise, coughs

or whatever. Watch your power meter too for clues that something might be amiss.

P a g e |8

FT8 Operating Guide

◄

The Spinal Tap approach , also known as Mediterranean

Syndrome (“All knobs to 11”) will create more mayhem and

complaints than FT8 QSOs. Resist the urge.

With many FT8 stations using QRP, someone running,

say, 100 watts or more stands out from the crowd …

but not in a good way, especially if they are not hearing

callers. Similarly, those running 50 watts to large

beams on a wide-open band: that’s a lot more ERP than

most FT8ers. However, QRO may well be necessary

and appropriate on marginal paths.

Automatically report callsigns and

Aside from QRO being antisocial and usually reports to PSK Reporter by selecting

unnecessary, if your signal is too strong, it may be dirty F2 Settings → Reporting → Network

and may overload receivers and audio cards at the DX Services → Enable PSK Reporter

end, preventing your signal from decoding reliably. Spotting. On the PSK reporter map , if

Take your cue from the signal reports you receive: if you others receive you much stronger

are getting positive reports, you can probably do just as than you receive them, your receive

well (maybe even better) with a fraction of the power. capabilities need some attention,

Remember: decibels are logarithmic. Cutting your and/or you may be running excess

4

.5

power in half will reduce average reports by just 3 dB;

cut it by half again to lose another 3 dB, and so on. If

you are receiving mostly negative

or zero reports, you are in the

power. [Tnx tip Martin G0HDB]

right region. I normally adjust

my transmit power to get

reports between 0 and -10 dB.

If you receive a 58 report ► but

you’re not using SSB, something

may be seriously amiss!

4

.6

If you are routing transmit audio

from the sound card to the front-panel microphone input on the rig, be sure to turn off the radio’s

speech processor and any audio shaping/profiling when using digimodes to avoid distorting your

signal. Radios with a rear-panel line-level input especially for digimodes, or a special ‘data’ mode

that automatically disables the processing (such as the K3), tend not to suffer issue. [Thanks for

the tip Joe W4TV]

Take care not to exceed your radio’s rated power output for digital modes.

Each FT8 over lasts 15 seconds. Transmitting at 100% duty cycle for 15 seconds

may cook your finals, especially on bands or antennas where the PA is less

efficient. Check the radio manual for advice – seriously, read the manual.

Listen for additional fan noise. Feel the radio case for excess heat. If you smell

smoke, you’ll wish you had paid attention to this issue before it escaped.

P a g e |9

FT8 Operating Guide

4

.7

Although FT8 is a weak signal mode, not a QRP mode

per se, please keep your transmit power down. Be

nice! Generally on HF, if a path is open, just a few

watts will do. Put your amplifier on standby. Turn

down the wick to QRP levels. Try it! If you don’t get

any responses at all, try 10 watts, maybe 20 or 30. If

you find that you routinely ‘need’ 100 watts or more,

that is a strong hint that your feeder and antenna

system are inefficient, or you are flogging dead bands.

Check for corrosion and loose connectors. Try making

a simple halfwave dipole as a comparison antenna.

You will find that you can receive better if your

antenna is in good shape, and – trust me – good

reception is kinda useful for DXin’.

There are situations where QRO, up to

your license limit, is both appropriate

and necessary, for instance CQing on a

closed band, hoping to catch DX as the

band opens, or calling someone weak

(

below, say, -20 dB). Occasionally, we

experience one-way propagation as if

there is giant diode in the

a

ionosphere: DX stations are loud but

cannot hear us. Maybe they have high

QRM their end. Maybe there is a tilt in

the ionosphere. Maybe they have

badly designed or operated systems.

4

.8

Near the low end of the range, Signal-to-Noise Ratios

“All SNR values from the decoder limit

are of dubious value due to how they are calculated ► down to minus infinity lie just below

the decoder threshold and estimates

of SNR near that threshold can have

huge variance despite only being a

few percent different in signal

strength. The WSJT-X decoders limit

these potential outlier estimates to

an artificial floor which is known to be

just below the lowest possible true

The SNR figures compare the strength of the signal (50

Hz wide in the case of FT8) to the noise across the 2½

kHz bandwidth typical of an amateur SSB receiver:

that’s 50 times the signal bandwidth (17 dB). So a -17

dB SNR FT8 signal is on a par with the noise, making it

virtually inaudible. For comparison, CW is copiable by

ear down to about -15 dB, slightly above the noise ▼

SNR value achievable from the mode

as determined by rigorous application

of information theory.”

[

Tnx Bill G4WJS]

The cough gauge ►

I also noticed by accident that when I cough

the gauge goes up into the red.”

“

Ah, that’ll be because your PC microphone is

active. Try selecting the soundcard input from

your rig. Or dose-up on cough syrup.

P a g e |10

FT8 Operating Guide

5

Important: receive levels

5

.1

The bar graph audio level meter in WSJT-X or JTDX should normally

read about 30 dB on a ‘dead’ band, increasing to about 50 dB on an

active band with about a dozen stations QRV simultaneously, higher

still on an HF band buzzing with life and lots of strong FT8 signals. If

the level goes too high and turns red, you are reaching the

compression point in your sound

The bar graph bar should card and may be over-driving it,

normally

showing

be

green, causing distortion and sampling

acceptable errors in the ADC (Analogue to

▲

The audio level bar

levels. If it turns red, Digital Converter) that, in turn,

there’s too much or too reduce the ability to decode FT8

graph reminds me of

Star Trek’s medical bay

little received audio.

signals. You might even damage

your sound card.

5

.2

Here’s how to set the audio input level to WSJT-X or JTDX on a

Windows system, step-by-step:

1

2

. Right-click the Windows loudspeaker icon at the bottom right

corner of your main screen and select Recording devices ►

. Select the sound card input that receives audio from your radio

(preferably a “line” input if there is one on that sound card,

otherwise the “microphone” input) then click Properties

►

3

4

. Select the Levels tab and set the slider near the middle

of the range. Hopefully it is most linear in this region.

Trust me, it doesn’t need to be precisely in the middle.

. If there is a balance control, set both audio channels to

the same level. On a radio with dual-receivers feeding

the left and right channels on a stereo output, or with

two radios, you may want to monitor each channel

separately with two instances of WSJT-X or JTDX , for

example monitoring FT8 and WSPR simultaneously.

5

. Click OK to close the Levels tab, then

open the Advanced tab ►. Check that

the default format is 48000 Hz (DVD

Quality), the preferred sampling rate

for WSJT-X and JTDX . The default

default rate is often 44100 Hz (CD

Quality): converting that to 48000 Hz

wastes CPU cycles, creates resampling

errors and degrades decoding - best

avoided if 48000 Hz is available and

works on your system (it may not). 16

bits are sufficient: more is OK.

P a g e |11

FT8 Operating Guide

6

7

. Click OK and OK again to exit the Windows sound settings.

2

. Launch WSJT-X if it is not already running . With your

Clap your hands or shout out: if

you see the bar graph level flick

up, you may have selected the

PC’s microphone rather than the

radio input! Oops. Easily done.

radio OFF, check the bar graph at the bottom left corner

of WSJT-X main screen. The level should be at or near

zero, flickering red. There may be a few dBs of noise

generated in your sound card, or a little stray pickup on

its input (e.g. some AC hum if it is poorly shielded). If

you see a lot of input, something is wrong. Check that you have selected the radio audio input

to WSJT-X under F2 Settings  Audio. The input should show the sound card line or

microphone input from the radio that you checked/adjusted above.

8

. Now turn ON your radio and tune to a quiet

In contrast to VHF/UHF, there are

band, with the attenuator off, RF gain up high

usually lots of strong FT8 signals on the

HF bands at peak times: “weak” HF DX

signals are generally only weak relative

to other HF signals, rather than weak in

absolute terms relative to the noise

floor, so strong signal handling and

and preamp set as normal. You should hear just

a little background noise on the radio - band

noise plus noise generated in the receiver

itself. The bar graph in WSJT-X should be read

about 30 dB. You may need to adjust the audio

output level from the radio (the Line Out level if

dynamic range tends to be more

you have that facility, otherwise the AF level) and

important than sensitivity on HF.

until WSJT-X shows about 30 dB.

9

. If your radio has a fixed (non-adjustable) line level output or one

It might be worth

comparing different

USB ports for your

USB sound system or

that cannot be reduced to about 30 dB on a dead band, have you

plugged the radio line output into the microphone socket on the

PC sound card by mistake? Or have you selected the microphone

input rather than the line input on the sound card? Check the

labels on the sound card inputs and the sound card settings. If

there is no “line in” but only a “microphone” input, and no way to

turn off the microphone preamplifier in the sound card settings,

you might need an external attenuator (e.g. a potentiometer) in

rig connection: some

are noisier than

others in my

experience.

the audio lead from your radio to reduce the audio level feeding

into your PC sound card, or you may need to use the radio’s headphone output rather than

the line out, using the radio’s AF gain control to set the quiescent level on the WSJT-X bar

graph to (yes, you guessed it) about 30 dB.

1

0. Now tune to band that has some life in it, using

If there is so much band activity that

the band selector on the WSJT-X main

the bar graph is near the top of the

screen. You should hear FT8 signals on the radio

scale and turning red, turn off the

and see signal blobs on the waterfall. The WSJT-

radio’s preamp, turn on the attenuator

3

X bar graph should read about 40 to 70 dB , still

and/or reduce the RF gain to bring the

in the green, and after a period or two you should

levels back down to the green zone.

see some decodes appear.

That’s it, you’re done! To avoid having to repeat this whole process, you might like to make some

notes about the settings though, just in case ‘someone’ fiddles with ‘something’.

2

If your radio has a built-in sound card and USB interface, you won’t be able to use the sound card while the radio is switched

off … but to simulate no audio input, maybe you can tune to a dead band and disconnect your antenna? [Tnx tip VE3AND]

3

The dB values here are decibels relative to a reference level, the digitized signal value 0001.

P a g e |12

FT8 Operating Guide

5

.3

Even having set up your receive levels carefully, and if you

are using a high quality modern rig with a high dynamic

range, particularly strong signals often appear wider than

others … but don’t be too quick to blame it on someone

running excessive power and splattering. They may be

locals, and if they are DX it could just be that the path

happens to be wide open between you.

When conditions are favourable,

I’ve often seen genuine QRP DX

signals showing plenty of red on my

waterfall.

Remember, FT8 is

designed for weak signal DXing.

The yellow fuzz either side of a solid red blob like this ► is probably just

a display artifact i.e. low-level skirts on the digital filter that generates

and colours the waterfall. Despite appearances, most FT8 signals are

clean in fact. That said, I would avoid CQing close to a strong signal like

this (in the fuzzies), even if I chose to

More tips about using your

transmit at the same time as him.

There are generally better places elsewhere.

filters and AGC below.

“

Many amateurs have completed WAC, WAS, DXCC, and other

awards using these modes, often with low power and simple

antennas .”

Work the World with WSJT-X, Part 1: Operating Capabilities

K1JT, K9AN and G4WJS, QST October 2017

P a g e |13

FT8 Operating Guide

6

Other software settings

FT8

FT4

None

3.575

None

7.0475

10.14

14.08

JT9

1.839

3.572

None

7.078

10.14

14.078

4

1.84

6

.1

Preferred frequencies for digimodes are normally expressed as

VFO “dial” frequencies in megahertz, with the radio set to USB

or DATA mode ► The actual transmit frequency is higher by the

audio frequency according to where the red Tx goalposts sit

above the waterfall.

3

5

7

.573

.357

.074

1

0.136

4.074

.2

.3

Dial frequencies for various modes can be checked and

customised through the F2 Settings  Frequencies tab. If you

make a mess of the settings, right-click the table and select

1

8.1

1.074

4.915 24.919 24.919

8.074 28.18 28.078

18.104 18.104

21.14 21.078

2

‘

Reset’ to recall all the default frequencies for all the supported

modes.

In order to avoid your transmit frequency continually jumping or being pulled around by successive

callers, in WSJT-X, select (tick, check) the Hold Tx Freq option; in JTDX , click the yellow Lockd TX=RX

button to turn it to green Tx/Rx Split. Even with Hold Tx

Freq or Tx/Rx Split selected, you can still put your Tx

where you want by shift-clicking the WSJT-X waterfall or

right-clicking the JTDX waterfall, and you can call someone

on their frequency (simplex) if you really must: simply hold

Ctrl as you double-click their CQ message, or shift-

click/right-click your Tx to their frequency, or click the up-

arrow button to move your Tx frequency. It’s seldom a

good idea though, especially if you are calling a rare DX

station. Their frequency tends to get busy with callers.

6

.4

.5

Pick a readable font type and size under F2 Settings



General tab, particularly for the decodes. Personally, I

prefer sans serif fonts with a slashed zero such as Monaco

or Consolas ►. Your monitors, eyes and preferences may

vary, so fiddle with the fonts and font sizes until you’re

happy. FT8 is an experimental mode after all!

The watchdog (WD) timer is a vigilance

It's not good practice to transmit for too long

control , a kind of dead-man’s handle. If

while transmitting the operator appears to

have dozed-off for a defined period, the

trusty automatic watchdog springs to life,

shutting off transmissions that would

otherwise continue indefinitely, displaying

a red warning message. There are two

things you can do to stop this:

without a break: I recommend taking a breather

after 5 or 6 minutes max. The WD timer counts

down in the bottom right corner of the main

window. When the time is up and the Tx

disables, it’s worth checking that your transmit

frequency remains clear of QRM at the times you

would be transmitting. In fact, it’s not a bad idea

to QSY anyway since you may be QRMed by

someone too weak to see (hence the lack of

response to your CQs or calls), or perhaps

coincidentally they have been bitten by their

watchdog at the same moment as you!

1

. Kick the watchdog! A click anywhere in

the window (even between the buttons)

tells the watchdog you are still awake and

unexpired, resetting its countdown timer.

4

6

0m frequencies vary around the world: check your license and local bandplan for details.

P a g e |14

FT8 Operating Guide

2

. Give yourself more time. You’ll find the starting value for the countdown under F2 Settings then

General for both Tx watchdog and Tune ▼

6

.6

.7

In DXpedition mode with WSJT-X, the hounds’ watchdog timers are fixed

at 3 minutes. After calling the fox 6 times, our transmitters are

automatically disabled if we haven’t had a reply. We can simply click

enable Tx to continue calling the fox … but it’s a good idea, first, to take a

moment to check that our Tx frequency remains clear during the even

periods when we would be transmitting.

We are more

likely to be heard

by the fox on a

clear frequency.

This is DXing 101.

Select Auto Seq. Auto-sequencing works quite well

“The auto sequencer is doing the

with FT8, reduces operator stress and cuts down on

newbie operating errors (e.g. not selecting the next

message in time, not the correct one anyway). If

Auto Seq gets it wrong, you can override the auto-

selected message by quickly clicking the Tx message

button for your choice of message. If you do this

during the first few seconds of your transmission

equivalent of double-clicking each

response from your QSO partner ... A

QSO will be ‘correctly’ sequenced by

double-clicking each of your QSO

partner's responses as they arrive. This

is how you would normally use the

application in modes without auto-

sequencing like JT9 and JT65 although, of

course, you can click through the next

message manually as well: automation is

an aid not a necessity.” [tnx Bill, G4WJS]

(

during the synchronisation segment), the revised

message will probably be sent as intended. If you

aren’t quick enough, the message may be corrupted.

Alternatively, there’s the 100% manual option ►

P a g e |15

FT8 Operating Guide

6

.8

If you inadvertently select one of the Contest options under F2

Settings  Advanced in WSJT-X you will be perplexed to

discover weirdness in your generated messages and

sequences▼

Stop tinkering with random

settings or you’ll be sent to

the naughty step!

5

Deselect (un-tick) Special operating activity to resume normality.

5

JTDX does not support contests.

P a g e |16

FT8 Operating Guide

7

How to respond to a CQ, or call a specific station

7

.1

First set things up:

•

Set up WSJT-X or JTDX to control the rig using CAT.

Set the receive and transmit audio levels and the rig’s power level correctly.

Find a clear slot

on the waterfall

and shift-click

(

WSJT-X)

or

right-click (JTDX )

to set your

transmit

frequency there.

•

Enable/select

Auto Seq and

Hold Tx Freq.

Check the WSJT-

X

F2 Settings



General and

select Double-

click on call sets

Tx enable ►

Show DXCC entity

and worked before

status

decoded

highlights

CQ

messages that are

new ones for you on the Band activity pane.

Double-click on call sets Tx enable makes it dead easy to respond to a standard CQ message: when

you double-click a decoded message, WSJT-X does several things for you:

•

It puts the other station’s callsign and gridsquare (if they sent one)

into the DX Call and DX Grid boxes on the main window, displaying

the short path beam heading (if they sent a grid).

Select Tx messages

to Rx frequency

window to see your

outbound and

inbound messages

in contrasting

background colours

on the righthand

pane. The example

QSOs in Appendix F

show this.

•

It generates the standard messages you will send, with their callsign

and your report to them inserted.

It selects the appropriate transmit periods, even or odd, the opposite

of whichever periods the DX station is using.

It copies the decode you clicked to the bottom of the Rx frequency

pane on the right.

It selects message Tx 1.

…

and finally …

•

It sets Tx Enable so you will start transmitting when it’s your turn.

P a g e |17

FT8 Operating Guide

7

.2

Before you double-click a decode to call someone, select a suitable transmit frequency. Shift-click

(WSJT-X) or right-click (JTDX ) on a clear space on the waterfall to put the red goalpost there.

“

The CQing station doesn’t need to say up 3 or anything else. He will decode all stations in the

audio spectrum. You can call him at 300Hz or 2300Hz and it won’t make any difference. They

all display. You don’t have to (and don’t want to) move to his frequency. If there is more than

one station calling him, they will hopefully be spread all over the audio spectrum, not causing

QRM to the station trying to make a QSO or each other. If a bunch call on his frequency, they

just QRM each other and the guy CQing will be working those who are split. Additionally, if he

starts a QSO with someone close to your transmit frequency, your transmitter will be disabled

so you don’t cause him QRM. If you are transmitting further away, you can keep calling him and

he should pick you up as he works through the list of callers.” [Tnx Gary AG0N]

Three strategies for picking your Tx frequency

1

. The easy approach is to pick a clear frequency (i.e. a blank column on the waterfall) and hope

it is also clear for those you want to contact. This strategy works well on a quiet band but is

less effective when the band is chockablock. There may be no blank columns! A less-busy

frequency may be your only option e.g. partially overlapping one or two other stations, or

somewhere near the left or right sides of the waterfall (although the DX station’s filters may

cut off more sharply than yours).

2

3

. If the DX station doesn't appear to copy you at all for a few transmissions, move to a different

transmit frequency. Likewise, if a QSO appears to stall, the DX station repeating the same

message to you several times … eventually giving up on you to work someone else.

. Avoid calling ‘simplex’ on the same frequency as a DX station, except as a last resort. Naïve

FT8 users tend to call ‘simplex’, QRMing each other in much the same way as a pileup on the

legacy modes. The rarer the DX, the worst this problem becomes. He will struggle to copy

anyone reliably, unless by chance most stop calling and the frequency goes quiet.

[

Tnx Jeff, WA1HCO]

7

.3

You can call anyone you like … but you’ll find it more productive

to call stations you can actually copy, at the right moment.

There is a silent DE in most

messages. “S9A ZL2iFB RF80”

means “S9A DE ZL2iFB RF80”.

‘

Stations you can actually copy’ are the ones sending the

second callsigns in messages containing two callsigns e.g.

S9A ZL2iFB RF80

ZL2IFB S9A JJ30

ZL2IFB S9A -23

ZL2IFB S9A RR73

TNX TIPS GARY

These messages

were all sent

by ZL2iFB:

These messages

were all sent

S9A ZL2iFB -21

S9A ZL2iFB RR73

TNX NEW 1 73

by S9A:

If you intend to call S9A, the best way is to browse through the lefthand Band Activity pane to find

a standard message sent by S9A (i.e. one with some other callsign first, then S9A, ending with a

locator, signal report or RR73 message) and double-click that. Your system will normally start

calling him at the start of his next listening period. If he is in QSO with someone, your transmission

may be sent at the same time as the station he is working … which may cause QRM unless you are

transmitting on a clear frequency (hence the previous advice). If not, quickly click Halt Tx to stop

transmitting and wait until the QSO is over before clicking Enable Tx to start calling.

P a g e |18

FT8 Operating Guide

7

.4

If you cannot find a

Please, only call stations you can copy! From the DX perspective,

it is very frustrating to be called by people that are evidently not

copying us. We waste our valuable time pointlessly responding to

them when instead we could be working the deserving.

Remember that DX stations are often in remote, low-noise

locations, hence they hear pretty well. If you live in a town or city

surrounded by nasty switchmode PSUs and other hams, you will

struggle to hear the DX … so wait patiently until you decode at

least one message from the DX, and spend the time wisely. Try

turning your beam, improving your station, locating and replacing

those nasty switchmodes with nice linear supplies, or persuading

your significant others that rural life is wonderful. The grass really

is greener out in the countryside.

message sent by the DX

station in your Band

Activity lefthand pane,

that’s probably because

you are not receiving him

well enough to decode his

6

messages . There is little

to no point calling him as

you will probably not copy

his response, even if he

copies and responds to

you. Your transmission is

wasted.

7

.5

The software prepares (‘generates’) the standard messages Tx 1 through Tx 5 when you:

•

Double-click a decoded message. The callsign of whoever sent the decoded message appears

in the DX Call box and is inserted into the standard messages Tx 1 to Tx 5, along with your signal

report for him (i.e. the signal-to-noise ratio in decibels as measured on the most recent message

received from that station) in messages Tx 2 and Tx 3.

Type a callsign into the DX Call box and then click the GenMsgs button.

7

.6

This is how JTDX looks while it is decoding

This shows JTDX while it is

the latest audio capture from the radio ▼

transmitting message Tx 2 ▼

The grey radio button next to Tx 2 ▲ shows

which message will be sent next …

… and the Tx 2 button turns green ▲ and enable

Tx goes red while it is being transmitted.

6

Browsing back through the Band Activity pane is a pain because it resets to the bottom as each new batch of decodes is

displayed. We can stop it updating by de-selecting the Monitor button or turning off the receiver. One day maybe we’ll

persuade the developers to let us freeze the pane by mousing into it, thawing it when we click a decode or mouse away.

P a g e |19

FT8 Operating Guide

7

.7

.8

.9

If the other station copies you calling him and responds to you, you’ll see his response (usually

your-callsign his-callsign his-report-to-you) appear at the bottom of the Rx Frequency pane, and

Auto Seq will automatically select your next message to send (Tx 3 - with an R before the report

confirming that you have Received his

If you are not prompted to log the QSO, check the

report to you). He’ll respond with an RRR or

configuration settings. The software may be

RR73 message, and you will send your 73

logging QSOs automatically and silently for you

message. The box will pop up prompting

as they are completed … or it may not be logging

you to log the QSO and Enable Tx will be

QSOs at all. Oh oh.

unset, and that’s it, you’re done!

7

If double-clicking a CQ message doesn’t do anything, that usually means the DX station is (perhaps

inadvertently) using a free-text message rather than one of the standard predefined message

types. The auto-responder doesn’t recognise it as a CQ message, so doesn’t know how to respond.

Even if a free-text message happens to contain the string “CQ” and looks like a CQ (such as “CQ

ZL2 M0NKR”), it still isn’t interpreted as a CQ message. The solution is either to double-click a

different decoded line from the same DX station in the hope that it is a standard message, or

manually type his callsign into the DX Call box, click Generate Std Msgs, select your Tx 1 or Tx 2

7

message , and click Enable Tx to start calling him. This is a reminder not to get too fancy with your

CQ calls.

7

Aside from shift-clicking the

waterfall, another way to shift your

Tx frequency is to nudge it 60 Hz LF

using shift-F11, or 60 Hz HF using

If you change your mind after QSYing, these fixed-step

nudges are readily reversed, whereas there is no easy way

to revert automatically to your previous Tx frequency

after shift-clicking or right clicking.

shift-F12.

.10 Keep an eye on the decodes while you are calling someone. DX

stations sometimes disappear, perhaps temporarily or

permanently going QRT, dropping in QSB or QSYing. If you

notice other stations calling the same DX you are calling, stop

transmitting for a cycle or two to figure out what’s going on:

maybe the DX has swapped between even and odd slots to

evade a stalker. Make sure you are calling him when he is

listening! Maybe he has moved a few kHz away to use

DXpedition mode (fox-n-hounds).

Although there’s a lot going

on in the minute or so it

takes for an FT8 QSO, most

of it is automated ... and,

trust me, it gradually

becomes less stressful as

you log more QSOs and gain

confidence.

8

7

.11 In order to set your primary Rx and/or Tx audio frequencies, pick from these ten options:

1

2

3

. Click somewhere on the waterfall to put your Rx there⁹.

. In WSJT-X shift-click or in JTDX right click on the waterfall, to put your Tx there.

. In WSJT-X right-click on the waterfall for the option to put both the Tx and Rx there.

7

If you forget to select Tx 1 or Tx 2, WSJT-X will send your CQ message Tx 6 instead. Probably not what you wanted!

I say ‘primary’ because the software attempts to decode all the signals it finds, wherever they happen to be across the entire

8

audio bandwidth as seen on the waterfall. The green Rx frequency marker allegedly indicates the region that is decoded first

and deepest, although in practice on the HF bands I don’t notice any difference. It is safe to ignore the green marker.

9

I find no reason to do this. See previous note. The software supposedly moves the Rx marker to the audio frequency of

whoever we are working but on my system it often doesn’t … and yet I make QSOs just fine. Ignore the green marker!

P a g e |20

FT8 Operating Guide

4

. In WSJT-X, uncheck Hold Tx freq to have your Tx jump to

another station’s frequency as you double-click their CQ

message (a bad idea, especially when calling a DX station

busy with other callers).

In JTDX , Hold Tx freq is

always active and cannot

be disabled. Cool.

5

6

7

. Enter your choice of audio frequency directly into the Tx or

Rx box.

. Click the little up or down arrow buttons next to the Hz label in the Tx or Rx frequency box to

shimmy up or down 1 Hz per click. Click and hold to send a staccato series of clicks.

. If necessary, click to put Windows’ focus on the main WSJT-X screen or the waterfall, then

press F11 or F12 to slide your Rx left or right respectively. Hold the Ctrl key to increase the

rate of slide from 1 Hz to 60 Hz per click.

1

0

8

9

. Click to focus then hold shift and press F11 or F12 to slide your Tx left or right respectively .

. Double-click a CQ message from someone specifying an auto-QSY VFO frequency (not

recommended on HF).

1

0. Stay put while you read the online user guide or press F3 and read about the shortcut keys, or

F5 to read about the special mouse commands (commands for special mice!).

7

.12 Two distinct things, working together, determine your transmit and receive RF frequencies:

1

. Your transceiver’s VFO frequencies on transmit and receive. Normally these are the same

‘simplex’) but they may be different (‘split’ or ‘crossband’) and

(

2

. The audio frequencies generated by the selected PC sound card as directed by WSJT-X or JTDX .

When you select a band in WSJT-X or JTDX , it

commands your CAT-connected rig¹¹to set

the VFO to the specified frequency such as

1

4074 kHz for 20m, and optionally sets the

mode according to the F2 Settings  Radio

tab ►. If your radio offers a data mode, try

that. If not, use USB (on all bands) but be sure

to disable any speech processing.

7

.13 The red goalpost marker above the waterfall

shows the audio frequencies of the tones that would be generated if you transmitted on the

chosen VFO frequency … but … if you have sensibly selected one of the Split Operation options

under F2 Settings  Radio, and positioned the red goalpost marker towards the left or right sides

of the waterfall, things may get interesting:

•

The Rig setting can use the rig’s built-in split function to move the transmit VFO (usually VFO B)

relative to the receive VFO (usually VFO A) if it needs to compensate for a difference in the

audio frequencies generated (see below).

1

0

1

Be lucky: on my system, the shift F11/F12 thing stops working after WSJT-X has been running for a while. Just my luck.

If your rig is not CAT controlled, you’ll have to change frequencies the old-skool way using its knobs and buttons.

1

P a g e |21

FT8 Operating Guide

•

The Fake It setting can QSY the main VFO on transmit if it needs to compensate for a difference

in the audio frequencies generated (see below), and QSY back to the original VFO frequency on

1

2

receive .

The ‘difference in audio frequencies generated’ comes about because very low or very high audio

frequences are likely to be attenuated by your transmitter’s audio filtering . Most amateur

sideband transmitters have a restricted audio range of approximately 200 Hz to 3 kHz, sufficient

for intelligible speech, similar to the telephone, but their filters attenuate or roll-off audio

frequencies at the lower and upper edges of the range.

1

3

Using Split Operation, WSJT-X and JTDX can move the transmit VFO HF or LF in 500 Hz steps while

generating audio at the same number of 500 Hz steps in the opposite direction. This is how the

Split Operation function works with Fake It ▼

Example 1 shows someone with the red goalpost sitting just above 2200 Hz on the waterfall. At

that audio frequency, the rig’s sideband filtering may start to roll-off the level, reducing his output

signal strength. Therefore, the software shifts his transmit VFO 500 Hz HF and simultaneously

drops the generated audio 500 Hz LF to just above 1700 Hz, right in the sweet spot between 1500

to 2000 Hz where the rig’s transmit audio passband is liely to be flat. The net result of those two

shifts is that his output signal emerges as if by magic just above 2200 Hz where the red goalpost

sits, but at full strength.

12

Fake it works even on single-VFO radios provide they are CAT controlled. If you are using a boat-anchor or basic rig without

CAT, it’s a good idea to keep the red Tx marker away from the left and right ends of the waterfall. Keep to the safe middle

ground.

13

Naïve ops who notice low rig ALC levels [when they are transmitting from either end of the waterfall] sometimes increase

the PC audio output to the point that the transmitter’s microphone input is overloaded, causing them to transmit audio

harmonics that we see as ghostly barcodes. ‘Rig’ or ‘Fake it’ reduces this possibility.

P a g e |22

FT8 Operating Guide

Example 2 shows what happens when the red goalpost

was

Recently

I

noticed that

I

is set below 1500 Hz on the waterfall. The VFO and

audio both shift by 500 Hz in opposite directions to keep

the audio frequency in

sometimes being spotted on FT8,

apparently using a different TX audio

offset than I had set. Eventually I

twigged that the rig was not operating

in split mode: the split command from

JTDX was being rejected by the radio

due to a mode conflict between the

K3’s VFOs (or something!). Clicking

The sweet spot is

deliberately restricted to

the upper part of the rig’s

flat audio passband such

that if the audio stages are

accidentally over-driven,

any audio harmonics

should be attenuated by

the filtering, producing

cleaner signals.

the sweet spot while

again the output signal

ends up on the

intended frequency at

full strength.

the rig’s front panel A▶B button twice

cleared it up, and now I keep an eye on

the LCD display for the SPLT indicator,

especially after changing bands.

So, don’t panic if you

see your rig’s VFO move

when you go to

transmit: it’s all under

1

4

control .

14

Well, usually it is under control. There are occasional reports of the rig ‘walking’ a further 500Hz LF or HF on each over –

presumably something screwy in the CAT comms. Cue the IT help desk: “Have-you-turned-it-off-and-on-again?”.

P a g e |23

FT8 Operating Guide

8

How to call CQ

8

.1

Hopefully by now you have your system working on

both receive and transmit. Get ready to call CQ by:

•

Setting the Hold Tx Freq, Auto Seq and Call 1^s^t

options on the WSJT-X main window, or AutoTX,

AutoSeq and Tx/RX Split in JTDX .

Clicking the Tx 6 message box or button, or hitting

F4, to select your CQ message if not already

1

5

selected: look for the Next selector blob ►

8

.2

Before you start calling CQ, study the waterfall for at

least a couple of cycles. Look for two things: (1) a suitable space in which to transmit, ideally a

clear column; and (2) any strong/local stations already transmitting. If you’re lucky, there will be

no angry red blobs on the waterfall from signals strong enough to trigger your receiver AGC, and

none radiating wideband noise or audio harmonics to interfere with your reception and decoding

of weak DX signals. If you are having trouble from one station, it helps to synchronise your

transmissions with him so that both of you transmit and listen at the same time – so choose the

same even or odd cycles. That’s not always possible, for instance if there are strong or poor quality

signals from both even and odd-cycle transmitters. So, do the best you can. Fiddle with your radio

settings if that helps e.g. reducing RF gain or adding attenuation; turning your beam away from

the QRM; using high/low-cut filters or a notch; turning off the AGC. Perhaps take a break or try a

different band. Above all, keep your cool. This is all part of the challenge – and the ‘fun’ – of DXing.

Rise above it. Be like DX boss.

8

.3

Now, to CQ, simply click the Enable Tx

button to start calling CQ. That’s all

there is to it! If everything goes to

plan, within 15 seconds or so the rig

The software can only ‘Generate Std Msgs’ if you

double-click a decoded message, or enter a callsign into

the DX Call box first: otherwise the only message it can

generate is Tx 6, the CQ message with your own

callsign, assuming you have configured that under F2

Settings → General tab.

will go into transmit and you’ll see the

CQ message at the bottom left of the

being

main

WSJT-X

window

transmitted.

15

Being able to pre-select the next message to be sent can be handy during the course of a QSO, for instance to send a specific

free-text message at the end of the current QSO, even while your RRR or RR73 message is being sent. However, neither WSJT-

X nor JTDX handle this very well. In particular, our chosen or custom-written free text messages are often reset to the default

boring 73 message, summarily erasing our planned message without warning. It’s a bit of a juggling act, sometimes, manually

wrestling with the autosequencing logic. It can help to turn off the autosequencer temporarily – just remember to turn it back

on afterwards!

P a g e |24

FT8 Operating Guide

8

.4

When someone responds to your CQ, Auto Seq takes you though the conventional QSO sequence,

automatically. It sets up the messages with both callsigns, and sends them their report using

message Tx 2, or Tx 3 if they have already sent you your report. Next one of you sends RRR

meaning ‘all received’ or RR73 meaning ‘all received, best wishes and thanks for the QSO’. Either

of you may send Tx 5 containing the standard 73 message or something bespoke – just 13

characters, though, similar to SMS/TXT messages. Provided the message you transmit contains

the string “73” somewhere, WSJT-X interprets that as the final message of the QSO and pops up

the logging panel for you, assuming you are using the F2 Settings  Reporting option “Prompt me

to log QSO” ▼

1

6

At the same time, Enable Tx is automatically unset , giving you a moment to savour the QSO ... or

click Enable Tx to start the sequence again with a fresh CQ.

The requirement to click Enable Tx to re-start the QSO sequence is not an accidental

oversight in the software but a deliberate, conscious choice by the team behind FT8

and WSJT-X. By design, WSJT-X will not robotically fill your logbook for you.

8

.5

.6

If someone else has called you already (a tail-ender ), you can double-click their decode to respond

without sending another CQ first, but you must wait until the previous QSO is complete and your

final message is sent: if you double-click too soon while your 73 message is still being transmitted,

the 73 message will be aborted and you’ll start calling the tail-ender instead, perhaps transmitting

a corrupted and undecodable message. That’s not cool.

st

Call 1 automatically responds to the first decoded With both Enable Tx and Call 1 selected,

caller – literally, the caller whose message pops out WSJT-X will automatically respond to the

of the decoder first, anyone from anywhere who first decoded station who calls you after

responds to your call: if you want to choose which you have logged the previous QSO, even

st

callers to QSO, turn off Call 1 and double-click the if you don’t send a CQ. It doesn’t queue

decodes from the callers you want to work, ignoring up callers though, so they have to call you

the riff-raff. You have more autosequencing options at the end of your QSOs. JTDX does

with JTDX , so read the notes and try them out.

appear to queue premature tail-enders.

8

.7

If the auto-responder responds to someone but you

would rather have responded to or called someone else, within the first second or so of your

transmission you can hit F4 to clear the current respondee, then double-click a decode from the

wanted station. The F4 step is necessary, unfortunately: it would be easier if we could just double-

st

click the decode to respond to that one, even with Call 1 selected, but without F4 the double-

click is ignored.

1

6

s

t

T

h

i

s

h

a

p

e

n

s

i

f

y

o

u

h

a

v

e

c

h

o

s

e

n

D

i

s

a

b

l

e

T

x

a

f

t

e

r

s

e

n

d

i

n

g

7

3

i

n

F

2

S

e

t

i

n

g

s

→

G

e

n

e

r

a

l

,

o

r

i

f

n

o

t

a

n

d

y

o

u

a

l

s

o

h

a

v

e

C

a

l

1

st

selected. Personally, I think that’s a bug in WSJT-X. I find it inconsistent and disconcerting to discover that the Call 1 option

affects the end of QSO behavior. Maybe it’s just me.

P a g e |25

FT8 Operating Guide

8

.8

Customize your CQ calls by editing the Tx 6 message in the

format “CQ XXXX ZL2IFB RF80” where XXXX consists of UP TO

FOUR LETTERS e.g.:

Be careful with this: you only

get to play with those 4 letters.

If you enter 5 letters or include

numbers or punctuation, your

CQ call becomes a free-text

message with the 13-character

maximum: on receipt it is not

automatically interpreted by

WSJT-X as a CQ message, hence

nothing happens if a recipient

double-clicks it. So don’t do it!

•

A continental indicator such as AF, AS, NA, OC or SA, or

17

two such as AFEU or NASA (!), or DX , UK, USA, ASIA, AP

or APAC (Asia/Pacific), or your antenna direction such as

EAST or NNW, or EULP or JALP, or LEFT (as in left coast) …

•

An explicit exclusion such as NOEU, NOJA or NONA

One or two state indicators such as VT, RI, NDSD …

One or two letter-only prefixes such as PJ, JA, VKZL, VP …

SPLT, SPRD or BLOB meaning “Please call me split not

simplex! All I see is a nasty red blob on my Tx frequency!”

Q codes etc. may be handy if

someone

you

notice

apparently responding on

your Tx frequency to your

CQ but you cannot decode

their messages.

•

A Q-code such as QRZ, QRO, QRP, QRM or QSY, or an

abbreviation such as AGN or WEAK

IOTA, SOTA, TEST, IGC etc. indicating that you are operating

from an island or summit, or in a contest or

challenge, and/or would prefer to contact someone

who is

Custom messages tend to evaporate

when the software regenerates the

standard messages e.g. when you

log a QSO. Don’t blame me!

•

An abbreviated club name such as CDXC, ARRL, JARL,

RSGB or NCDX maybe

8

.9

If recipients double-click any valid CQ message, their

systems will generally respond regardless of their locations. Rude hams evidently don’t read or

don’t care about targeted CQs, calling even if they are nowhere near the target. It is up to the

CQer, then, to decide whether to make a QSO with them … or wait patiently in hope of a call from

1

8

someone in the bullseye.

“

As someone who has a very limited location for

antennas (they are all in the loft!) and for DX (I live in a

valley), I’ve found FT8 a brilliant way of achieving QSOs

that would be quite impossible with most other modes.”

Bryan G4KRO

17

DX means whatever the sender thinks it means. There is no formal or universal definition. Oh HF, it may mean another

country, another continent, the far side of the world, a top N most wanted DXCC, anything vaguely exotic, or something else

entirely. For those using microwatts, a mile or two may qualify as DX! For EMErs it could mean little green men from Mars.

18

JTDX gives us the option to auto-respond ONLY to targeted callers … but even JTDX doesn’t understand “CQ DX”!

P a g e |26

FT8 Operating Guide

8

.10 It’s entirely up to you whether to transmit, what to transmit, when

and where … but some hams get their knickers in a twist if you do

something unexpected or unconventional. It is conventional but

not mandatory to end HF QSOs with the exchange of 73 messages .

Some FT8 users feel

snubbed if they don’t

receive a 73, stubbornly

refusing to log the QSO

on principle. It’s their

choice. It’s only a hobby.

If you do not receive a 73 from the other

The golden rule is

party, tough: perhaps it got lost en route,

to log the QSO

swallowed up by the ionosphere. Get over

whenever we

it! If they stop sending or start CQing, it’s

send an R

message.

fair to assume they believe the QSO is complete so you are probably in

their log.

8

.11 The Halt Tx button is immediate – it aborts the current

transmission in progress (if any) and de-selects the

Enable Tx button so it won’t transmit at the start of the

next sequence. De-selecting the Enable Tx button,

however, allows the current transmission (if any) to

continue normally to completion. You don’t need to click

it at the very end of the transmission or wait until the

receive period – click it whenever you don’t want to

transmit in the next transmit period.

When you want to take a break, de-

select Enable Tx at any time during

or following your final transmission.

If you can, keep an eye on the

screen for a while longer in case of

a delayed response when your call

reaches the head of the fox’s

queue. He might bite anyway.

“

[Although] WSJT-X requests audio sample streams at 48000 Hz 16-bit depth, that does not

mean that other sample rates and formats are not supported. The operating system and audio

subsystem will convert to or from the nearest available hardware sample rate. While sample

rate or format conversions are undesirable, they are not necessarily problematic, e.g. some

conversions are trivial computationally such as reducing bit depth from say, 24-bit to 16-bit,

which only requires low order bits to be discarded, likewise down/up converting the rate by an

integral factor is also trivial such as converting a 96000 Hz or 192000 Hz input stream to 48000

Hz. On the other hand, converting a 44100 Hz input stream to 48000 Hz involves complex re-

sampling which is expensive and inaccurate and could even cause audio dropouts on a slow PC.

WSJT-X currently down samples to 12000 Hz as a first processing step on Rx, this is sufficient to

support an audio bandwidth of up to 6000 Hz which is all that is needed for the modes supported

by WSJT-X. We request a 48000 Hz stream as this is commonly available all almost all audio

codecs of suitable quality for WSJT-X use. Using higher sample rates adds no benefit, it simply

adds unnecessary computation for no gain in performance whatsoever. The same applies to bit

depths greater than 16-bit.”

Bill G4WJS

P a g e |27

FT8 Operating Guide

9

Logging digimode QSOs

9

.1

At the end of a QSO, JTDX and WSJT-X normally prompt you to log the QSO. In more detail:

•

‘At the end of a QSO’ means when you receive a Tx5 message, specifically a Tx5 message

containing the text “73”.

o Consequently, if you edit the generated Tx5 message, it is best to leave the “73” in there

so that the other party is prompted to log the QSO, or logs it automatically.

o If the Tx5 message is not sent to you, not received by you or does not contain the magic

“

<

73”, you will have to log the QSO manually by clicking the Log QSO button or typing

Alt+Q>.

1

9

•

I said ‘normally’ because if so configured, JTDX can automatically log completed QSOs:

o Tap F2 to open the Settings.

o Click to open the Reporting tab.

o In the Logging section of the form (top left), select (tick) Enable automatic logging of

QSO which de-selects Prompt me to log QSO if that was set (it is the default).

o Click OK at the foot of the form to save the settings and continue using JTDX.

9

.2

When a QSO is logged, two records are written to disk:

•

A text record is appended to a .log file, of the form:

021-09-06,03:50:33,2021-09-06,03:51:14,RV3ID,KO77,14.076359,FT8,-05,-19,,,

And an ADIF record is appended to an .adi or .ADI file, of the form:

2

•

<

call:5>RV3ID <gridsquare:4>KO77 <mode:3>FT8 <rst_sent:3>-05 <rst_rcvd:3>-19

qso_date:8>20210906 <time_on:6>035033 <qso_date_off:8>20210906

time_off:6>035114 <band:3>20m <freq:9>14.076359 <station_callsign:6>ZL2IFB

my_gridsquare:4>RF80 <eor>

19

Because the WSJT-X team is determined to prevent their software being used robotically to make and log QSOs

automatically, I understand WSJT-X does not natively offer automatic QSO logging. The JTDX team is less adamant, hence JTDX

can automatically log completed QSOs, which means less chance of completed QSOs remaining unlogged simply because we

neglected to click the log QSO button.

P a g e |28

FT8 Operating Guide

•

The text and ADIF log files are stored in your

AppData\Local folder. The easiest way to get to that

folder is to use File  Open log directory ▶

WSJT-X and JTDX use virtually the same log file name

(

wsjtx_log.ADI for JTDSX and wsjtx_log.adi for WSJT-

X) in their own directories (folders) within the

AppData\Local folder – a windows folder that is

normally hidden by Windows Explorer to stop inept

users messing up their systems.

•

On your system, your WSJT-X ADIF log file is probably

at %localappdata%\WSJT-X\wsjtx_log.adi You can copy and paste that string into the

Windows Explorer directory field. The %localappdata% bit is a ‘system environment variable’

that gets expanded by Windows, taking you to wherever the AppData\Local folder is located on

your see

www.freecodecamp.org/news/appdata-where-to-find-the-appdata-folder-in-windows-10/

“

With a few optional exceptions (“Fox” operation in FT8 DXpedition mode, and

contest operation), user action is also required to verify QSO details and submit

them for logging. In any event, by design WSJT-X requires that every QSO must be

initiated by a human operator. We do not like the idea of fully robotic operation

with modes like FT4 and FT8, and the WSJT-X software prevents it.”

The FT4 and FT8 Communication Protocols , QEX July/Aug 2020

P a g e |29

FT8 Operating Guide

10 Hinson tips: miscellaneous FT8 operating tips

This chapter is an assortment of answers to Frequently Asked Questions, blended with a bunch of helpful

hints contributed by experienced FT8 HF DXers.

1

0.1 Generally speaking, it’s best to turn off the rig’s noise blanker,

narrow filtering and fancy DSP Noise Reduction for digimodes:

let the sound card and computer software do its thing,

extracting signals from noises ... but … you may like to

experiment with the settings (e.g. IF shift, high- or low-cut or

your notch filter may reduce overloading and AGC depression

caused by strong signals such as W1AW news broadcasts or

over-the-horizon radar). Some users report good results with

the rig’s DSP noise filtering (e.g. +5 dB with NR on an Icom IC-

“

Don't ignore that narrow

CW filter in your radio! A CW

filter will pass narrow digital

modes just fine. While it is

generally a good idea to listen

wide so you can see all the

traffic in the band segment,

when you are trying to dig

that weak one out through

the cacophony it can help to

put your narrow filter on him.

Try it!” (Tnx Jim, NU0C).

7

200 according to Hans DK2XV, in the presence of switchmode

PSU QRM). There’s no harm in finding out for yourself.

Compare the results with and without DSP – see what works

best for you, producing the clearest waterfall, the most

decodes or the highest average reception reports.

Here's an example of the value of narrow filtering, captured on my WSJT-X waterfall ▼

The big red blobs on the lower left of this waterfall are a couple of local ZLs with massive FT8

signals on a wide-open 20m at peak time (one of them over-driving his rig’s audio input, causing

the ghostly barcodes around 1870 Hz). The red blobs at about 1850 then 1900 Hz towards the top

of the waterfall were from a Kazakhstan station calling me via the long path. I quickly raised the

lower edge of the K3’s filter to cut off the locals, preventing their signals from depressing the AGC,

causing the black/dark speckly area up to 1400 Hz with no big red blobs. At the same time, the

signals in the passband, including the UN7, became markedly stronger and we completed our LP

DX QSO.

This filtering trick works for any signal that you can locate on the waterfall. The waterfall itself

shows the effect of narrowing the rig’s filters and shifting the filter centre frequency. If your rig’s

filtering is not so flexible, using the RIT to shift strong signals out of the passband may help.

1

0.2 If you change the free-text message in Tx 5 but want to revert to the default message, simply

double-click the Tx 5 button. The other Tx messages can be regenerated on demand by clicking

the “Generate msgs” button (“GenMsgs” in JTDX ) provided the DX station’s call is still in the DX

Call box.

P a g e |30

FT8 Operating Guide

1

0.3 Messages are appended to the left and right hand windows in the sequence they emerge from the

logic. They are not - and unfortunately cannot - be sorted according to frequency, callsign, country,

strength, distance, worked before status, needed status or anything else and sometimes appear

distinctly disordered:

•

Messages emerge sequentially from each round of decoding, first the ‘easily’ decoded signals,

then the ones that took deeper analysis. Magic is happening here in the decoder algorithm –

don’t knock it!

Your transmit message might be sent to the encoder and displayed on the screen with its

current timestamp before a deep decode from the previous period is, belatedly, appended with

its earlier timestamp.

When you double-click a message, it is repeated at the bottom of the righthand window.

1

0.4 Especially when the band is humming and the DX is busy, spread

out! Any decoded message containing your callsign will be

displayed on your Rx frequency pane, wherever it is being

transmitted on the waterfall, so there is no need to work

simplex. Unlike the legacy modes, calling or working simplex is

generally not a good idea on FT8, especially with any popular

station since others will generally be doing the same, QRMing

each other. Hasan N0AN put it very well:

Calling someone simplex

while they are in QSO with

someone else is rude and

inconsiderate. If you do it to

me, I may deliberately ignore

you. If you were in the

shack, I’d give you a slap.

Don't call me on my Tx freq, as it is full of callers

Unlike conventional legacy modes, split operation is

Don’t forget that each party to an FT8

preferred by most FT8 DXers. The idea that split

QSO transmits in sequence. Even and

operation on FT8 “ties up two frequencies for one

QSO” and is therefore an inefficient use of spectrum is

a naïve misunderstanding. ►

odd periods are orthogonal and

should be considered separately.

Within each period, each party is

Rather than zero-beat to using one thin slice of spectrum, just

call someone on their 50 Hz wide. After they end their

working frequency, take a transmission, the frequency is

moment to shift-click your released for anyone else to use during

Tx signal (the red goalpost the next 15 second period. See

Split operating is not a

hard-and-fast

rule.

It’s not the law, just a

tip that experienced

FT8 DXers find works

better in practice than

simplex. Try it!

above

the

waterfall) Appendix E for a more elaborate

elsewhere on the waterfall, explanation.

somewhere quiet.

What does make inefficient use of our shared spectrum is when several people all pile up on the

same frequency, QRMing each other, leading to repeats, delays, abandoned QSOs and intense

frustration. Another inefficient practice is calling continuously or out-of-turn, especially calling

right on top of a QSO in progress – again something that is made worse by multiple people

attempting to use the same working frequency simultaneously. It’s not so much that zero-beat

simplex operating is inherently bad and patently it does work, rather that split works even better

on FT8.

P a g e |31

FT8 Operating Guide

1

0.5 Higher transmit frequencies towards the right of the

Spare

digihams. Stay within the FT8 sub-

1) Harmonics caused by overdriving something in the band: weak signal DXers using

a

thought for other

waterfall are slightly advantageous for two reasons:

(

audio chain are more likely to be blocked by your rig’s Olivia, JT65, JT9 and other

transmit filters [don’t rely on this though! Keep your digimodes, mostly above 2500 Hz

audio level down!]; and

2) On a busy band, decodes in the band activity pane

scroll past quickly in frequency order, so anyone CQing

or so on the waterfall, will not

appreciate you stomping all over

them. You may not even see their

signals on the waterfall: that’s why

it’s called weak-signal DXing!

(

towards the left of the waterfall is more likely to scroll off

2

0

the top of the pane . However, don’t go too far to the

right of the waterfall ►

If the station you are calling is

very weak, others who cannot

hear him may inadvertently

cause QRM by choosing his

frequency to CQ. You might try

sending a message or two

simplex to let them know the

frequency is in use. [Tnx tip Olaf

DK2LO]

Having said that, if someone you are calling seems to be

ignoring you, it may help to move your Tx frequency closer

2

1

to theirs , perhaps even simplex (not a good idea if they are

DX). It is possible they are not receiving FT8 signals across

the full sub-band shown on your waterfall, for example they

may be using filters or may have their VFO offset. Maybe

your chosen Tx frequency is busy with local QRM at their

end.

1

0.6 Especially when the band is busy, monitor for a couple of minutes before selecting your Tx

frequency. Look for a continuous blank column on the waterfall, ideally, and shift-click (WSJT-X)

or right-click (JTDX ) to move the red goalpost there. Here’s part of the waterfall around 18100kHz,

beaming at NA ▼ Not bad for low power DXing on a seemingly deserted band! If I was planning

to transmit in this range, I’d probably choose 1140, 1490 or 1650 Hz.

2

0

It helps to stretch the WSJT-X window towards the full screen height: I can see about 40 decode lines that way. In JTDX,

there’s room for about 45 decodes AND I can still see the waterfall showing about 6 periods right across the top of the screen.

If for some reason you are not using CAT control of the radio hence the “Rig” and “Fake it” split options are unavailable,

21

remember to keep the red goalposts in the central area of the waterfall.

P a g e |32

FT8 Operating Guide

1

0.7 You may need to shift your Tx every few minutes on a busy band if other stations encroach on you

such that the stations you are trying to work cannot copy you. Keep an eye on the waterfall and

decodes.

0.8 If you CQ, transmit in the same period as

I gather on 6m and other UHF bands (!), there are

the strongest signal/s on your waterfall to

minimize mutual interference. Transmit

when they transmit, receive when they

receive. Dance the DX dance in-step.

conventions on which slots to use when beaming

East or West … but what do I know? I’m an HF

DXer. On HF, we cope. We muddle through.

1

0.9 Keep an eye on what’s going on. It’s tempting to set the Auto

As with regular DXing, the key is

to listen more than you

transmit. It’s nature. Two ears,

one mouth, remember.

st

Seq and Call 1 autoresponder options, then start CQing or

calling someone and wander off ... but the sequencing

function is easily confused by custom messages, or by

messages received sequence out of.

0.10 If you are CQing, making a run of QSOs or

If your transmissions are being reported on

calling and working several people, take a

PSKreporter by stations wherever in the world

break every so often to check that your Tx

you seek to work, your chosen Tx frequency is

FT8 is extremely good at un-

presumably reasonably clear there.

frequency and period remains clear. In WSJT-

X, the easy option is not to re-Enable Tx

knitting interwoven and

overlapping signals, but

weak signals are more likely

to decode reliably on a

reasonably clear frequency.

immediately after you log a completed QSO -

skip a Tx period. The lazy option is to wait for the watchdog

timer to kick in. By taking a break, you may see other stations

transmitting on ‘your’ frequency and period, or encroaching on

“

Another technique I've found useful is, while transmitting, press Halt Tx, wait a couple of

seconds then press Enable Tx and look at the waterfall on your Tx frequency. Frequently if

your’ frequency remains open, others will be able to decode your transmission in spite of

‘

user-induced QSB.” [Tnx Bill AE6JV]

it ... so shift-click yourself somewhere else on the waterfall. If you don’t take a break, you might

think ‘your’ Tx frequency is clear whereas in fact someone else is sharing ‘your’ slot.

1

0.11 The assorted screenshots in this guide are from my PC with my radio and my preferences. Yours

may vary … so if you are going to make configuration changes, you might like to make a note of

the changes as you make them so you can restore your original settings if the changes don’t work

out.

0.12 If, when you start transmitting, you hear what

appears to be a single, plaintive, wavering tone in

the headphones (similar to Tune), check on the

lower status bar ▼ that you are not in, say, JT9

or WSPR mode. Narrow goalposts ▶ above the

waterfall are another clue. WSJT-X and JTDX

both support several modes. Try ‘em!

P a g e |33

FT8 Operating Guide

1

0.13 If for some reason you neglect to log a QSO and forget the

details (e.g. if someone emails you about a QSO with a

missing confirmation and they aren’t in your log), the QSO

info is probably stored in your ALL.TXT text file. Messages

you have received and decoded, plus your transmitted

messages, are saved sequentuially to ALL.TXT by default.

It’s a plain text file. If you are very active on FT8 with WSJT-

“

When I play with settings, I grab

my phone and grab a quick

screen shot of the setup screen

so I know I can get it back without

hassle.” [Tnx tip Gary AG0N]

X, the file grows quite large: rather than simply deleting it, it’s a better idea to archive it

occasionally in case you ever need to search for missing QSO info. JTDX makes this easier by

opening a fresh ALL.TXT file each month e.g. in August 2018, as if by magic my ALL.TXT

became C:\Users\Gary\AppData\Local\JTDX\201808_ALL.TXT

1

0.14 Don’t worry too much about your Rx frequency: you can safely ignore the dead green goalpost

above the waterfall, leaving WSJT-X to move it around for you. The software is decoding the entire

waterfall, all at once, right? Well, yes and no: apparently it focuses on the area under the dead

green goalpost, decoding first and more deeply there. So you might want to set the Rx frequency

manually if you are monitoring some juicy but weak DX, waiting for him to complete QSOs so you

know when to call. Also, on a busy band, the band activity screen scrolls too fast to ‘read the mail’,

whereas, with fewer messages, the Rx Frequency pane scrolls at a far more sedate pace.

1

0.15 Use the rig’s AGC or take care to adjust the RF gain control and attenuator whenever there are

strong signals on the waterfall. Overload in the receiver and/or sound card can mess with any

digital signal processing in your rig and on the soundcard including, WSJT-X’s decoding and

waterfall display. AGC is the easy option, preferably on a slow setting since the software copes

admirably with fading FT8 signals . Consider using your rig’s filters too.

0.16 Please don’t continuously call someone who is calling or

The software should automatically

working someone else, even if you are calling them off-

2

stop you calling someone simplex if

they respond to someone else, but

you should be keeping an eye on

things … and simplex operating is

not recommended anyway.

frequency . Be nice: wait your turn! It’s polite to wait

until the DX sends RRR, RR73, 73 or CQ before calling

them. If you call continuously, or try to barge-in on a QSO

in progress (especially simplex), you will simply waste

watts, create QRM, cause delay, and you may even be

blacklisted by the DX.

1

0.17 Use the waiting time wisely. Look at who else is QRV and where they are on the waterfall. Maybe

shift-click (WSJT-X) or right click (JTDX ) your Tx to a different, clear frequency. If you simply

continue calling, you may be missing out on even more exotic DX stations who are transmitting at

the same time as you!

22

JTDX is polite enough to stop us calling someone if they respond to someone else, regardless of our Tx frequency. WSJT-X

only stops us calling if we are transmitting on or close to the station we are calling. I consider that rude.

P a g e |34

FT8 Operating Guide

1

0.18 ... Talking of which, don't reflexively double-click to call that

unbelievably exotic DX station you just decoded - wait for another

transmission to double-check his callsign, meanwhile looking him

up on QRZ or Google. If it seems too good to be true, it is quite

likely a false decode, ”CQ XIXIMARIA” for instance, or “7T4W?0D

A+ O2”, or “ 8WL??GN10S77”! That said, there are some weird

and wonderful novice and special-issue callsigns QRV on FT8, so

don’t dismiss them all as freaky decodes. [Thanks John NA6L.]

The educated AP (a priori)

guesswork that can help

dig out deep deep decodes

is more error-prone than

the usual decoding so

you’ll see more exotica if

you enable AP decoding.

0.19 Tail-ending with FT8 is a bit awkward: first type the DX callsign into

the DX Call box and click Generate Std Msgs to set up the appropriate messages (or double-click

the DX station’s CQ message and quickly hit Halt Tx to abort your

If you find your Tx being

transmission if now is not the perfect time to call). Remain on your

carefully chosen clear Tx frequency to call and make the QSO (Hold

Tx Freq should be selected, remember): if you start calling the DX

off-frequency then suddenly shift your Tx to his frequency (simplex)

when he calls you, you will be joining the big red blob of other

callers, causing QRM.

“

pulled” around on each

QSO, select Hold Tx

Freq to stay put.

1

0.20 In a DX pileup situation, a shortened message sequence helps maximise

the QSO rate. To set things up for this, double-click message Tx 1 to skip

it (it will be greyed out). Now when you double-click a decode to call

someone, you will start with Tx 2 instead i.e. sending both callsigns plus

the report, rather than both calls plus your grid. Next, double-click Tx 4 to

toggle from the conventional RRR message to RR73, short for ‘Yup, got it,

thanks, let’s end the QSO right here: there is no need for us to swap 73’s

as well. Good luck with the rest of the pile, CUL, please QSL on LoTW...’.

Toggling works on

Tab 1. If you use

Tab 2, switch to

Tab 1 to toggle Tx

1

before returning

to Tab 2.

0.21 Shortening QSOs is a contentious practice, raising numerous intertwined issues:

•

The protocols for making QSOs (digimode QSOs particularly) are only partially defined and still

evolving, and anyway the protocols are not universally agreed and followed in practice.

Some hams send RR73 just once at the end of a QSO and evidently (for various reasons) aren’t

bothered whether the other party receives it or not. Too bad, that’s their choice.

Some hams send RR73 repeatedly, anticipating a response, and a few of them get upset if they

don’t receive it. Too bad, that’s their choice too.

Some hams send RRR once or repeatedly in the same way as RR73, and may or may not follow

that with a final message, that may or may not contain the string 73, and may or may not be

automatically logged (yes, a load more uncertainty there).

•

Some messages are sent but not received due to the vagaries of radio propagation, technology

and gremlins. This point, at least, I think we can all agree on!

Some dogmatic hams have fixed/definite ideas about what constitutes a QSO and hence may

or may not log QSOs that others believe complete. Too bad, that’s just how it goes.

Some amateur QSOs are technically incomplete, for example relying on non-amateur back-

channels or databases or guesswork to pass QSO information that was not successfully passed

on-air to the satisfaction of all parties. We’re exploring the limits of radio technology here.

•

Logged QSOs may or may not match if submitted to LoTW, Club Log, QRZ or other online logs,

depending on a multitude of factors, many of which are beyond the control of the individuals

P a g e |35

FT8 Operating Guide

concerned. Aside from checking for matches in real time, insurance QSOs are an option … but

a few hams bitterly resent duplicate QSOs. It’s a no-win situation.

•

Generally, we can’t tell for sure what our QSO partners are thinking unless they tell us (which

is unlikely to happen on-air during an FT8 QSO) hence we can only guess at their position re

ending and logging and confirming a QSO. ‘Good practice’ is not fixed or guaranteed.

Some hams see red if someone else dares to express differing opinions to them and appear

intransigent or intolerant, coercive even. A few

come across as belligerent bullies or trolls.

I’ve noticed some regular FT8 users

Some hams are simply bewildered by the whole

thing, don’t understand the issues or really don’t

care since, after all, it’s only a hobby. C’est la vie!

Instead of complaining, work more DX.

transmitting on low audio frequencies

at or even beyond the left edge of my

waterfall, while few use high

frequencies near the right edge, so I

may shift my VFO down by about 100

Hz from the usual dial frequencies.

Editing the default frequencies for

each band is another idea.

1

0.22 The default FT8 frequencies are suggested, not

mandatory. Aside from DXpeditions using other

chunks of the HF bands to separate their pileups from

the regular users, JS8 users are using separate chunks

too, and FT4 as well.

0.23 Stretch the waterfall graph to display the full FT8

subbband out to about 3000 Hz, and open up the

filters in your radio. The entire displayed region of

the spectrum should normally show a similar

background colour: if there are dark patches to the

left or right, your radio is probably attenuating low

or high frequencies, making it less likely that you

My K3 automatically resets the filter width

whenever I change bands or radio modes.

It’s worth stepping through each of the

FT8 frequencies, checking that in DATA

mode the filter is wide open (to 4000 Hz

on mine) and centred correctly (at 1500

Hz) on every band.

2

3

will decode weak stations there .

1

0.24 Why do we use “RR73” instead of “R73”? Good question!

One R is sufficient, but the two R’s plus two decimal digits

make a string in the same format as a grid square, hence the

FT8 coding scheme that normally passes grid squares using

the minimal number of digital bits can handle RR73 in the

same way, as if it were a grid. If instead you edit the text in

message Tx 4 to R73, that change turns the message into a

free-text message type with a limit of 13 characters in total …

which is often insufficient to pass both callsigns plus the

space and R73. We’re left with a paradox. Question: “When

is RR73 shorter than R73?” Answer: “When we are counting

bits in FT8”.

Since many of us are using QRP,

it might be nice to use RR72 to

indicate that, in the same way

that some QRPers sign-off QRP

by

exchanging 72’s. It might also

remind others to keep their

power down, where possible.

That would however require a

change to the software.

legacy

mode

QSOs

23

Selecting the “flatten” option – one of the controls under the waterfall - makes the spectrum appear more even but decoding

is unaffected (I believe). It’s just eye-candy.

P a g e |36

FT8 Operating Guide

1

0.25 This curious series of t h r e e s p a c e d - o u t M S K s i g n a l s followed by a steeply-sloping

strong FT8 signal on my waterfall ▼ indicated someone had a serious problem with their

transmissions, so serious in fact that they were undecodable, hence I wasn’t able to contact them

to let them know.

Shortly afterwards, they went QRT. Maybe there was a whisp of smoke …

1

0.26 Hardware devices of all sorts are identified and handled at a low level by Windows. Windows

provides Application Programming Interfaces through which drivers access the devices, and the

drivers, in turn, are used by application programs to do stuff. That’s a complex and problematic

arrangement. Device drivers are privileged yet bug-prone (raising security concerns) and can

conflict. Windows selects ‘default’ devices (generally whatever was most recently connected) and

hides devices from us that it believes are no longer attached, while at the same time retaining the

associated drivers allowing them to spring back to life instantly if they are ever reconnected.

Application

programs

sometimes insist on using

devices that are no longer

physically present. To spring-

clean your devices, open

Control Panel, right click

Device Manager and select

Run as Administrator. In the

Device Manager menu click

View then Show Hidden

Devices ► Expand the device

tree by clicking the small arrow

next to, say, Audio inputs and

outputs or Ports (COM and

LPT). One-by-one, right-click

any devices that are no longer

needed and select Uninstall. If a window shows up with a check box to delete the driver, do not

check this box as the driver might be needed for another device: uninstall the device only. Reboot

then check that unwanted devices are gone. [Tnx tip Bruce N7XGR]

1

0.27 Broken something? No transmissions? There are several possible reasons, so check things

systematically:

•

Is the radio going into transmit? Does the little red

light glow? Does the power meter indicate any RF

power out? If not, that’s an issue! Check the PTT

method section under F2 Settings  Radio ► If

you manually press and hold the PTT button on your

microphone, or the footswitch or use the front

panel TRANSMIT button, does the radio transmit

the FT8 tones during a transmission? If you are using

P a g e |37

FT8 Operating Guide

VOX, make sure the radio’s VOX sensitivity is high enough to trigger reliably at the audio level

you are using, and hold-in for the entire over.

•

Talking of audio level, make sure enough audio is reaching the rig from the sound card – neither

too little nor too much. See the section on setting transmit levels for tips on that. If adjusting

levels doesn’t resolve it, check the cable from the sound card to the line-in or microphone input

on the radio. Try plugging headphones or PC speakers into the sound card output to make sure

it is actually generating tones, then figure out why the audio isn’t getting to the radio. Is the

cable broken? Is it plugged in, to the right places?

Check for USB devices and hubs that automatically power themselves down due to apparent

inactivity. This function may be a useful power saver

but it is generally just annoying when sound cards or

rigs mysteriously disappear from the system. Using

Windows Device Manager, deselect “Allow the

computer to turn off this device to save power” for

each of your USB devices and hubs ▼

Also in Power Options under Control Panel, disable the

USB selective suspend ►

P a g e |38

FT8 Operating Guide

1

0.28 Broken something else?

No decodes? You’ll

probably find that the

program is not dead, just

resting. Check these ►:

(A) Set to FT8 mode [tnx

tip Jacky ZL3CW].

(

B) Rig on an FT8

frequency, on a band

that is open and

active, in data or USB

mode.

(

C) Monitor enabled

button bright green).

(

(D) Sufficient audio

reaching the software.

The

tricorder

thermometer

indicator

thing on the left

should also be green

with the level around mid-range or higher when the

band is busy.

Do you see a smattering of yellow

and red blobs on the waterfall? Is

Also check that the CPU is not overloaded: is your the rig on the correct mode and

computer underpowered? Isolating and decoding FT8 antenna? Can you hear the

signals takes quite a lot of processor oomph. If there weeeeeee of FT8 signals on your

aren’t enough CPU cycles available, it won’t be able to receiver? Is the rig on? FT8 is a

decode and display messages. Time to upgrade?

weak-signal, not a no-signal mode!

1

0.29 The stock DXing advice to LISTEN, LISTEN, LISTEN

applies equally to FT8 and other digimodes, well almost: I normally have the Rx audio turned right

down, the headphones sitting on the desk, so the digimode version is WATCH, WATCH, WATCH.

Learn to interpret the waterfall and decodes to figure out what’s

JTalert and some logging

happening. Are the DX stations CQing, searching-and-pouncing, or

programs can highlight

just quietly monitoring the band (in which case they may appear on

new DXCCs and new

PSKreporter , and if you call them speculatively they may just

grids as they appear in

respond!)? Notice how the signals grow stronger (redder) as you

the decodes.

turn your beam towards directions where there is better

propagation. Magic!

1

0.30 Call patiently. If someone is QRMing you, you may struggle to make or complete a QSO until they

stop. After 2 or 3 failed calls, try shift-clicking your Tx to a different clear frequency and continue

calling. If that still doesn’t work, maybe your signal is just a little too weak, so try turning your

beam, or wait until conditions improve. Hey, that’s DXing.

P a g e |39

FT8 Operating Guide

1

0.31 The waterfal settings take some trial and error to

customize for your system, screen, eyes and preferences. Click to select a slider then use the

Please read the user guide for details on the waterfall keyboard arrow keys to make fine

controls, and bear in mind that some changes are instantly adjustments: it’s easier than

obvious while others only become apparent later as the dragging the slider with the

waterfall is re-painted under various band conditions.

mouse.

0.32 If a stalker is pestering you for a QSO, constantly calling but

never sending you a report when you respond, or perhaps having started a QSO repeatedly sending

the same message over and over and over like a stuck record, here are a few things you can try:

•

Be tolerant. It is not easy to master FT8! The caller may have accidentally unselected Auto Seq

and neglected to select the next message manually, and may not even realise he is causing

problems. Hopefully he will soon catch-on. Perhaps he is distractedly reading the help file or

looking up these very tips ... well, we live in hope! Try sending a free-text message such as

“NEXT MSG PLS” or “CHK AUTO SEQ”.

•

Be patient. It is possible he is persistently sending the same message simply because your

acknowledgements are not getting through (e.g. your signal has dipped down in QSB or QRM),

so the next message is not appropriate. Personally, I’d give at least 2 or 3 repeats, up to 10 if

I’m keen to complete a DX QSO, especially if conditions are poor and signals are weak.

While you wait, browse to Time.is to double-check that your computer clock is set accurately,

especially if this is a frequent occurrence. Is your NTP software running? If you are using

Meinberg, under the Windows Start menu, select Meinberg then Network Time Protocol, then

click the Quick NTP status to display a text listing of the time servers it is using. Are there any

error messages, or is it all normal? The offset (time error) should typically be just a few

milliseconds e.g. somewhere between +2 and -2, as here ▼

•

Check your beam heading and power: perhaps your signal is simply too weak for the stalker to

decode. Try beaming directly at him (short or long path) and maybe give it a few more watts.

Open boiler door, add anthracite. Tweak your dilithium crystals. Do the DX waggle dance.

Conversely, deliberately beam away from the stalker and turn your power down, in the hope

that having noticed you disappear from his waterfall, he’ll crawl away to his cave while you

continue working other people.

Take a break: maybe someone else is transmitting on top of you. Skip a transmit period to check

whether your Tx frequency is deserted without you.

P a g e |40

FT8 Operating Guide

•

Shift-click (WSJT-X) or right-click (JTDX ) your Tx elsewhere on

the waterfall. If all that achieves is to drag the stalker to your

new frequency (probably because he has unwisely chosen not

to select Hold Tx Freq) and he is still not responding to you,

Last resort: give up!

Change mode or band.

QRT. Make a cup of tea.

Walk the dog. Stroke the

cat. Poke the fire. Browse

the online help . Hug a

stranger. Tidy the man-

st

QSY again but this time toggle the Tx even/1 option to swap

periods, transmitting your CQs at the same time as the stalker

is plaintively calling you. Maybe before long when he notices

that you have disappeared from his waterfall, and stops to

listen for once, he’ll see you already making QSOs with other

savvier hams, and the penny may finally drop.

cave.

Email Gary with

better tips .

1

0.33 New versions of WSJT-X and JTDX install themselves with new Windows start menu shortcuts,

leaving the old shortcuts there, cluttering up the place. To Spring-clean your start menu, open File

Explorer then copy and paste the following string into the address box:

%

ProgramData%\Microsoft\Windows\Start Menu\Programs

You may see something similar to this ► The redundant

JTDX entries are directories containing shortcuts to

nowhere. With admin rights, I simply delete them apart

from the current version – although even that could go too

as I normally use a desktop or taskbar icon to launch JTDX ,

not the start menu. For bonus marks, create a desktop

shortcut to that directory to make it easier to find again.

1

0.34 Don’t get too carried away with the custom messages and

shortcuts. There is clever programming under the hood to

optimize communications with the standard messages in FT8,

which means some compromises. On top of that, you only have

It is worth composing and

storing few free-text

messages in the Tx 5 quick-

a

select list (under F2 Settings

1

3 places to fill in each free-text message from a very limited

→

Tx Macros) especially if

like me) you are not an

accurate typist under

pressure e.g.

character set (just numerals, capital letters, spaces and a few

(

2

4

punctuation characters) . In particular, you will soon discover

that most users are reliant on Auto Seq, which is easily confused

by anything out of the ordinary.

Custom final messages are less of an

Try it! There’s more

to the hobby than

swapping calls, grids

and reports!

issue though.

Free-text (Tx 5)

messages containing “73” normally

trigger Auto Seq to realize the QSO is

over and should be logged - although

clued-up and patient ops can

and perhaps TNX TIPS GARY

continue conversing using 13-character free-text messages

indefinitely, holding back on the 73 until the conversation is

about done.

24

The JT-mode character set consists of A-Z, 0-9 and the characters + - . / ? and space. The characters @ # < and > have special

meanings and are not transmitted. They are reserved for testing or otherwise as described in the WSJT-X User Guide. The

slash is best avoided except as a callsign separator, although it and the full-stop (period) let us send short URLs. Use a redirector

to shrink longer URLs down to less than 14 characters e.g. BIT.LY/FT8OP

P a g e |41

FT8 Operating Guide

1

0.35 Composing short yet meaningful TXT-like free-text messages in the time available requires

thought, skill, dexterity and luck. JTDX has an annoying tendency to revert Tx 5 to the default 73

message without warning, callously wiping out whatever cunning phrase I had composed and

intended to send, if it needs to re-send one of the previous messages. At the crucual moment,

“

TNX M8 73” becomes “ZL7DX ZL2IFB 73” and I’ve missed my chance to send a custom greeting to

a pal. So, keep an eye on the screen … and be lucky.

1

0.36 Once you have things set up, maximise use of your screen and minimise the

temptation to fiddle with the settings by hiding the

waterfall controls and menus. Simply clear/unset these

two boxes ◀ ▶

0.37 With so little information exchanged in each 15 second over, a sequence of even the most efficient

and succinct QSOs in FT8 hardly qualifies as running - more of a jog. The pace is easy enough once

you get the hang of it (it took me a few hundred FT8 QSOs). Here’s a screenshot during a leisurely

3

0m jog one ZL evening ▼

I started by finding and then CQing on a clear frequency with Auto Seq and Call 1^s^tboth selected

as usual. The program automatically responded to a decoded caller, taking us through the

conventional sequence of overs until the Log QSO pane appeared when I received a 73 message

signalling the end of the QSO. All I had to do then was click the OK button to log the QSO then

click the Enable Tx button to have the program re-start CQing after it had finished sending my 73

message. If another caller called me (before or after my CQ), Auto Seq generated the standard

messages and started a QSO with them. Meanwhile, I was easily able to work, catch up with

emails, browse QRZ.com etc. on the other screen on my dual-screen Windows desktop.

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FT8 Operating Guide

1

0.38 Are you as confused as me over whether a station is transmitting on the odd or even timeslots? If

you normally start a QSO by double-clicking a decoded CQ call, it doesn’t matter: WSJT-X

automatically selects the appropriate timeslot in which to call them.

But what if you want to call someone who is not CQing, perhaps just

finished working someone else? What if you start calling someone but

JTDX colour-codes

the time box and

they disappear without a trace? It’s worth checking that you’re odd/even selector to

transmitting in the correct even/odd period, not doubling with them.

Mike W9MDB pointed out a simple way to tell is to look at the final digit

make it even easier.

of the timestamp for their transmissions: if the times end in a zero, they are using the even slots,

so we need to call them on the odds. Times ending in 5 indicate they are odd (!). If that’s still too

st

hard to figure out in the heat of the moment, here’s a Hinson tip. Simply make sure the Tx even/1

selector resembles the last digit of the timestamp e.g. if it is 5, the selector box should be filled like

this , if zero the selector box should be empty like this ▼:

Maybe you nudged the

big knob. Maybe the

software kicked the CAT.

1

0.39 Keep an eye on the waterfall. If you notice FT8 signals shifted towards the left or right side, check

that your rig’s VFO frequency is correct for the band you’re using.

0.40 If you find yourself sending many repeated messages and failing to complete QSOs because the

other stations disappear or abandon you to work someone else, you may not have enough

radiated power. If your signal is too weak, other people will get partial copy and will miss some

decodes. Experienced DXers will hopefully notice that your signal is weak, and will patiently persist

as long as you are trying to complete a QSO … but inexperienced or impatient DXers tend to give

up too soon when conditions are tough. So, the answer is:

P a g e |43

FT8 Operating Guide

•

Make sure as much of your generated power as possible is actually radiated – ideally with a

short run of low-loss feeder and an efficient well-matched antenna (no need for an ATU). If you

want to work DX, you will do best with an antenna that has a low angle of radiation such as a

quarter wave or half wave vertical, a fullwave loop, or an inverted-L or T (top-loaded vertical)

…

or of course some sort of beam (the hexbeam for example – small, lightweight, works well).

As a bonus, a good DX antenna will increase the strength of DX signals you receive, so there will

be more DX on your waterfall to work!

•

Make the best of conditions and propagation. As you change bands, notice whether the

waterfall is ‘lively’, busy with loads of signals, or ‘quiet’, or ‘dead’. It takes more luck and often

more power to work stuff when the band is not in good shape. For this reason, it helps to be

able to use several HF bands, choosing whichever

DXing is a bit like fishing – we cast out

one happens to be the best at the time you are on

the air.

many CQ calls to catch the odd DX fish,

and bagging the occasional ‘big one’

Rather than just CQing, try calling stronger

stations, the ones with more red on the waterfall.

Make full use of the tips in this guide e.g.

transmitting split on a quiet frequency, at the right

moment (when someone is CQing or has just

completed a QSO, not during their QSOs) with

everything carefully adjusted (e.g. accurate clock,

audio levels in the green). Some stations won’t

hear you or won’t want to work you, some will …

so be prepared to call several stations for each

completed QSO. This is a normal part of DXing.

makes it all worthwhile. Personally, I

enjoy the ‘fighters’ most of all – QSOs

that are challenging to make due to

poor conditions, QRM etc. are all the

more satisfying to complete and log.

It’s a real achievement! The fisherman

is just as important as his tackle: every

time we get on air is a chance to

practice and hone our skills,

occasionally trying new tricks. It’s not

only about bagging the catch – enjoy

the chase!

•

Be patient and persistent yourself.

“

FT8 is designed specifically for propagation conditions such as multi-hop

sporadic-E at 50 MHz – circumstances where signals are weak and fading,

openings short, and quick completion of reliable, confirmable contacts is

particularly desirable.”

“

Work the World with WSJT-X, Part 2: Codes, Modes, and Cooperative Software

Development ”, K1JT, K9AN and G4WJS, QST November 2017

P a g e |44

FT8 Operating Guide

1

0.41 Setting the dead green goalpost Rx marker to

monitor a specific DX station can be awkward:

•

If you can find him on the waterfall, simply click

the left edge of his signal – that’s the easy bit but

quickly locating his signal on a busy waterfall can

be tricky.

Double-click to select the

numbers in the Rx frequency

the

frequency numbers using

the numeric keypad, ending

with Enter or Return.

•

Alternatively double-click one of his decodes to set up

your messages and start calling him (unless you hurriedly click

Halt Tx).

box,

then

type

Or type the audio frequency listed on his decodes into the Rx

2

5

frequency box on the main WSJT-X or JTDX screen or if you

are close, click the up or down arrows to fine-tune ►

1

0.42 While you are CQing and waiting for a response, keep an eye on the decodes for DX callsigns on

the left. You won’t decode DX stations that are transmitting at the same time as you, but you may

decode their callers during your reception periods.

0.43 If you need a QSO with someone who is calling CQ to a different area, pick one of these:

•

Call them anyway, once or twice, on a different frequency (split) so as not to QRM any callers

they may have from their target area. Don’t call them continuously, especially not simplex.

Instead of calling them specifically, make directed CQs to their area in the hope that they will

see you and respond to you if they wish.

Patiently wait and watch. If they stop CQing, or drop the specified target, pounce: call them!

1

0.44 With so much going on, especially when the band is busy, I sometimes got confused

over who I’ve just worked and logged. Thanks to an idea floated on the WSJT reflector ,

I wrote a simple batch file to call Windows PowerShell to display the last few QSOs from

the WSJT-X log, updating itself as each new QSO is logged. With the black and grey

PowerShell window shrunk down to just a narrow strip at the edge of the screen, it

shows the callsigns I have most recently logged ►

To do this for yourself, the Windows PowerShell command line is:

powershell.exe get-content %LOCALAPPDATA%\WSJT-X\wsjtx.log -tail 3 -wait

Courtesy of VE2EVN, the Linux equivalent is:

JTDX shows us the last callsign

tail -n 3 -f ~/.local/share/WSJT-X/wsjtx.log

“Logd” on the lower status line ▼

25

The text “Rx” and “Hz” currently within the frequency setting white boxes should really be outside the boxes. That simple

change would make it even easier for us to click or double-click anywhere in the box and enter the audio frequency number,

without having to worry about the Rx and Hz text also being selected.

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FT8 Operating Guide

0.45 WSJT-X routinely writes a WAV file of

1

received audio to disk while it processes it.

Even if you configure WSJT-X not to save

its WAV files using the obscure option

“

None” under F2 Settings  Save ►, it still

does. The reason is that normally the WAV

file is deleted automatically by WSJT-X

about 10 seconds after the processing is

completed (giving us time to save it if we

decide to do so). However, when you exit WSJT-X,

the current WAV file is abandoned, remaining

orphaned on disk. If you start and stop WSJT-X

repeatedly, you’ll eventually discover an orphanage

full of abandoned WAVs, cluttering up your hard

drive. Some users have reported hundreds of

orphaned WAVs.

It’s worth clearing out the orphans from time to

time, either manually (using the housekeeping

function on the File menu ►) or using a simple batch

file with the following Windows command line

(

perhaps the very same batch file that displays the

end of your WSJT-X ADIF log ):

del %LOCALAPPDATA%\WSJT-X\save\*.wav

1

0.46 If you change your mind or mess up your

typing while hurriedly editing the free-text

message Tx 5, you can instantly reset it to

the standard 73 message by double-clicking

the Tx 5 box ► but be careful about

precisely when you do it: annoyingly, the

double-click also changes immediately to

sending that message if you are

transmitting a different message at the

time, and offers to log the QSO.

1

0.47 Show the grids you’ve worked on a Google map using an online

mapper by WG7J . The mapper accepts ADIF log files up to a certain

size above which it fails silently so, if you have a large log, you’ll need

to pre-process it using this grid extractor utility by W9MDB to

generate a much smaller ADIF containing just one QSO per grid.

Green grids are confirmed, reds aren’t, yet. Mouse over for info.

Note: some hams give out and may even confirm the wrong grids ►

It is fairly obvious when their grids put them in the sea, unless they

were /MM at the time. Or swimming. Walking on water perhaps.

Do us all a favour: double-check your own grid square , please,

especially if you are confirming it via LoTW.

P a g e |46

FT8 Operating Guide

1

0.48 What constitutes a valid, complete QSO is another zombie topic, one that has been raised,

discussed, kicked around and buried on the WSJT reflector many times. Cutting to the chase, there

is no consensus among the ham community on this … hence when we are in QSO with someone,

we don’t know which way they think. Some of our QSO partners will steadfastly insist on

exchanging 73s with us, some won’t even send 73s, and

If you believe a QSO is complete,

quite a few more are in the ‘don’t care either way’

bracket. A few don’t even bother logging their QSOs (license

log it and hope that the other

guy also logs it. If you believe

conditions notwithstanding). Specifying and coding the

your QSO is incomplete, wait

software for such ambiguity on the part of the people we are

and hope that the other guy

contacting is, let’s say, challenging. Even if we were able to

keeps on trying to complete as

set our own preferences with a tick-box somewhere, we still

long as you, and then logs it.

don’t know what’s happening at the other side of the QSO,

so it’s left to the operator. Personally, I consider my QSOs complete when we have made a

connection sufficient to copy each other’s callsigns and exchange a few more bits of information

such as our reports. On FT8, when I’ve sent an RRR or RR73 message, I log the QSO.

1

0.49 Different amateurs sharing the same station can set up personal WSJT-X or JTDX profiles to suit

themselves, using the -r [name] command line modifier originally intended for using alternative

rigs with different settings. [Name] is just a handy label for the profile, such as the callsign (no

spaces).

For example, if I launch WSJT-X using WSJT-X -r ZL2iFB

it sets up a environment just for me, with a ZL2iFB

subdirectory to hold my ADIF log, ALL.TXT and .WAV

files, plus the .INI configuration file holding the default

settings which I would then customize to suit my

preferences (or more likely copy across from the

unnamed profle I already have). It reminds me that I

am using a custom profile for ZL2iFB by showing that

name on the window title.

If I close WSJT-X and then re-launch it using WSJT-X -r

ZM4T, it sets up another environment for the club,

with its own log, WAVs etc. in a separate ZM4T

subdirectory. We can then choose between the two

setups whenever we launch WSJT-X, with any config

settings being saved to the respective profile.

The easiest way to choose between profiles is to

append the -r [name] modifier to the Target for the

icon that launches WSJT-X, renaming the icon

accordingly ►

P a g e |47

FT8 Operating Guide

1

0.50 Does RF get into your computer and mess things up

when you transmit? The ideal solution is to reduce

the amount of RF in the shack, for example by siting

and feeding your antennas some way away using

balanced line, or good quality coax with a balun or

choke at the feedpoint of a balanced antenna.

While you mess around with earthing,

baluns and chokes, order some well-

shielded USB cables with copper braid

giving more than 95% coverage. Gold- or

silver-plated contacts, and maybe a few $

Earth bonding at the shack end can also help, as

well as running QRP.

more,

suggest

above

average

performance for USB cables, and audio

cables too for that matter. Don’t bother

with Oxygen Free Copper though: last

time I checked, plain old copper conducts

very nicely, thank you. I have no problem

with my timbre and sound field.

If that’s not enough, try putting suitable ferrite

_c_h_o_k_e_s₂6 on the PC cables. Split-core clamp-on

2

7

chokes are easy to fit . Physically routing the

cables, and perhaps re-siting the whole computer,

further away from your radio, amp and feeder may

help too.

In JTDX , there are additional autosequence

options to determine how the system responds

to callers. Look under AutoSeq on the main

menu bar and feel free to experiment ►

AutoSeq3 (“Call based on end of decoding”) suits

me. I prefer “Max distance instead of SNR” to

respond to more DXey callers first, and I’m

perfectly happy to work people more than once:

I’m friendly like that.

1

0.51 If you use a dual-monitor setup with WSJT-X

running on one monitor, leaving the other for

logging and other stuff, WSJT-X usually

remembers but sometimes forgets which

monitor it belongs on when it launches. It’s

annoying to have to drag or Windows-arrow it to

the other monitor each time. Fixing that

annoyance is a bit hit-and-miss. Here’s the trick that works for my USB-connected second monitor:

•

Temporarily disable the second display in Windows Device Manager.

Launch WSJT-X. It should open on the working display.

Re-enable the second display in Device Manager.

Drag or windows-arrow the WSJT-X main window and waterfall to the other monitor.

Close and restart WSJT-X to check that it has got its monitor memory back. If it hasn’t, you’re

on your own, sorry!

2

6

L L

Choose an HF-rated ferrite mix with an A value of at least 2,000 to add enough inductance. With A values in the low

hundreds, VHF-rated ferrites are cheaper (often free!) but add little impedance at HF.

The larger HF-rated cores, including man-sized circular toroids, are better as you can pass the cable through them several

27

times. The choking inductance increases in proportion to the number of turns squared e.g. 2 turns have 4 times the inductance

of 1 turn. Use thin, flexible cable with small or no connectors to squeeze more turns into a given core.

P a g e |48

FT8 Operating Guide

1

0.52 Most of us choose to upload the callsigns and locators we are decoding to PSKreporter.info , where

they can be flagged on a map. The PSKreporter screenshot ▼ for instance, shows roughly 25

yellow blobs - FT8 stations across South America, Africa and Europe being received by a German

station on 17m in the preceding 15 minutes.

The map is dark because this was in the wee small hours of his morning … when he wouldn’t

normally expect to be working DX on the high bands.

“The duties of a travelling watch inspector for a big railway system are

much more arduous than one might imagine. One system pays $18,000

per year for this purpose only. It takes the assistant inspector two years to

visit all the inspection points on the lines and each test of a watch lasts 72

hours. If it varies six seconds in that time, it is rejected.”

[

Popular Mechanics, January 1905]

[

In today’s money, $18k is worth about $½m]

P a g e |49

FT8 Operating Guide

11 Special callsigns

1

1.1 Deep within the technical specification of the FT8

protocol itself, the format of “standard callsigns” is

defined quite specifically and narrowly ►. This

reduces the variety of callsigns that the protocol

needs to handle, hence limiting the number of digital

bits required to code them. However, some special

event, compound and commemorative calls are so

“

A standard amateur callsign consists

of a one- or two-character prefix, at

least one of which must be a letter,

followed by a digit and a suffix of one

to three letters. Within these rules, the

number of possible callsigns is equal to

…

somewhat over 262 million … Since

is more than 268 million, 28 bits are

“

special” that the original FT8 protocol simply could

2

8

2

not accommodate them within the 28 bits reserved

for callsigns in most of its messages (e.g. CQ calls,

reports and RRR or RR73 messages)

enough to encode any standard callsign

uniquely.” [WSJT-X User Guide]

1

1.2 Although special callsigns of up to 13 characters can be included in free-text messages, they are

not interpreted as callsigns: they are simply arbitrary text strings. If someone double-clicks one of

those decoded free-text messages from some exotic DX in the hope of calling them, they would

be out of luck, even if the free-text message includes “CQ”. The software does not know what to

do with the message except display it to the frustrated user! It does not automatically enter the

full callsign in the DX Call box, nor does it include it in the generated messages for their response

due to the bit-shortage.

1.3 Standard callsigns with some

conventional location modifiers

(

e.g. typical CEPT-type compound

calls with ITU standard/DXCC-

approved country prefixes followed

by a slash) are handled by the

software, passing the full callsign in Tx

1

and Tx 6 but only the home callsign

part in the other messages. If I were

to nip over to, say, Auckland Island,

my callsign might be ZL9/G4iFB so my

generated messages for a typical QSO

would be these ► Notice that the

ZL9/ prefix is only sent in my Tx 6 (CQ)

and Tx 1 (initial response to caller) messages. The list of

prefixes and suffixes that are treated in this way is

available from the Help menu on the WSJT-X main screen

Other uncommon situations are

not explained in the help e.g. if a

station has both a prefix and a

suffix, or if two compound-call

stations are in QSO. Perhaps you’d

care to experiment to find out what

happens, in which case please let

me know how you get on.

(

with Menus selected). Those specific “type 1” prefixes

and suffixes (about 350 of them) are encoded and sent in

as few bits as possible, allowing two full callsigns to be

included in some generated messages. Some unlisted

“

type 2” compound callsigns (such as /M, /MM and /W3)

may be sent without the other callsign in some messages.

P a g e |50

FT8 Operating Guide

1

1.4 According to Claude Shannon’s information theory , the total number of digital bits in the payload

determines the amount of information that can be conferred by an individual message. In 77-bit

FT8, callsigns can be compressed down to hash values which are transmitted, then expanded back

2

8

to callsigns on receipt . However since the compression routine is lossy, at the receiving end

there are several possible expansions of a given hash … so which is the correct callsign? The answer

is found by checking back through recent decodes to find the callsign that was transmitted in full

at some prior point, and which gives a matching hash value. You may notice this process

happening from time to time

as the hashed callsigns may be

shown in angle brackets ►

Notice that, in that particular

example, DL7ACA – a perfectly

ordinary and conventional

German callsign – has been hashed to reduce

the number of bits required because the

other callsign in that message, SX60RAAG, is

special and needed more bits. Either callsign

Hash collisions (where different callsigns

compress to the same hash values) are a

possibility, along with CRC and AP failures. If

you see a truly bizarre callsign (not merely

may be hashed.

special), it is probably a bust.

1

1.5 Here’s an example of the hashing

process at work ►

Having just

launched JTDX and tuned to a DXcluster

spot for 9LY1JM on 17m, the first seven

decodes all displayed the <…>

placeholder in place of the DXpedition

callsign, indicating that the callsign was

being passed as an as-yet-unrecognised

hash code.

Subsequent decodes showed 9LY1JM’s

2

9

callsign after someone had sent the

DX callsign in full, hence JTDX was able

to hash it and match up its hash value

with the hash value sent by other callers, displaying the corresponding DX callsign for me rather

than <…>

1

1.6 Hashing isn’t a precise method to pass callsigns. Hash values are ambiguous. If, coincidentally,

two or more callsigns with the same hash values are both active, the software may choose and

display the wrong one. The software should always send the sender’s full callsign un-hashed at

least once in a QSO in order to be crystal clear, although it may need to hash the other callsign in

the message to save bits.

2

8

Hash codes for special callsigns are calculated and cached as they are received, ready to match against any subsequently

transmitted. When WSJT-X is closed, the cache is cleared and it takes a while to rebuild the cache after it restarts.

29

Not 9LY1JM themselves, unfortunately, since I could not copy them! The software can hash either callsign in the two-callsign

messages, so by chance someone must have sent a message containing a hash of their own callsign with the DX callsign in full.

P a g e |51

FT8 Operating Guide

1.7 Hovering the mouse over the Tx 1

1

button in WSJT-X pops-up an

ambiguous message ► stating that

toggling Tx 1 is ‘not allowed for type 1

compound call holders’ but the user

can press ahead and skip Tx 1 anyway.

The pop-up message is in fact an

instruction, not a statement of fact.

‘

Not allowed’ actually means ‘Do not

do this’. Don’t do it!

1

1.8 If the operator foolishly ignores the

instruction, skips Tx 1 and calls a station with “A caution to those of us who often bypass the

a compound callsign using Tx 2, the called Tx 1 message (calls and grid) and start with Tx 2

station’s Auto Seq responds with Tx 3 which (calls and report). If you are calling a DX station

omits the call of the station to whom they are with a special callsign, when the DX station

responding. This is a recipe for confusion responds, none of the messages in his

when there are several callers, often the case transmitted sequences will have your callsign in

since compound calls tend to be DX them. There is no way to know for sure that the

travellers. Regardless of whether our callers DX station is responding to you or another

send Tx 1 or Tx 2 at us, and regardless of station. The fix, when calling stations with

what kind of callsign we are using, we should special callsigns, is always to start with Tx 1.”

always respond with the caller’s callsign in

[Rick K1HTV]

our first message to be clear who we are

3

0

working .

1

1.9 The same issue affects both parties to a QSO involving a special

callsign. Stations with special callsigns who skip Tx 1 when calling

other stations may be frustrated to discover that their Tx 2 messages

are mostly ignored. The reason is that their special callsign gets

transmitted as a hash code that is displayed as <…> on the receiving

end unless by chance the recipient’s system happens to have

WARNING

Repeat after me:

do not skip Tx 1

Do not skip Tx 1.

Do not skip Tx 1!

previously received a message containing the full callsign, enabling it to match up the hash codes.

Recipients see someone repeatedly sending cryptic messages of the form “<…> +10” at them.

They are unable to respond properly because their systems do not know who to respond to. The

auto-sequencer robot is quite clever <…> but not bloody clairvoyant!

3

1

1.10 Likewise stations with special callsigns are unable to make contest QSOs on FT8 because the

contest exchange does not leave sufficient bits to send their special callsigns in full. There simply

aren’t enough bits available. FT8 falls a bit short sometimes … but not always ▼

3

0

I believe this is a design requirement for the software. Not doing this qualifies as a design flaw.

Special callsign holders can still contest using legacy modes with character-wise encoding such as CW, RTTY and PSK. Don’t

31

shoot the messenger, or the developers: it is one of the inevitable compromises of trying to squeeze quarts into pint pots. Rant

at Mr. Shannon or the bit tax. Or apply for an ordinary, common-or-garden, plain, simple and most of all short callsign! ꢁ

P a g e |52

FT8 Operating Guide

1

1.11 To explore the way various messages and callsigns are handled in FT8, check out “ft8code.exe” in

the WSJT-X program directory. Run it from a command line with a message as a parameter in

quotes to find out how the message would be encoded, sent and decoded. For example, if I

wanted to send the message “CQ E5/ZL2IFB/P RA01” via FT8, ft8code tells me that’s a nonstandard

call so my message would be transmitted as “CQ E5/ZL2IFB/P” omitting the grid ▼

This is HF Voyager , an

experimental scientific

buoy (a Wave Glider

solar-powered drone)

floating across the Pacific

tracking whales … and

amusing itself by making

FT8 QSOs en route under

the callsign KH6JF/MM.

Did you work the robot?

Got your QSL card yet?

P a g e |53

FT8 Operating Guide

12 DXpeditioning with FT8

1

2.1 There are pros and cons to using FT8 on DXpeditions:

•

On the upside, it is a popular HF mode, good for DXing even for those limited to low power and

basic or stealth antennas. It can make short openings and marginal paths productive.

On the downside, the maximum QSO rate is normally

A competitive CW, SSB or RTTY

op on a good station can sustain

a rate of 200+ QSOs per hour,

maybe 250 or more for a similar

level of operator effort - so

that’s potentially 4 or 5 times as

many DXpedition QSOs per

hour using legacy modes.

about 60 QSOs per hour using the standard protocol.

In practice, experienced digimode DXers (such as Roly P29RR)

can sustain a rate of about 50 FT8 QSOs per hour, provided

they have the ability to concentrate intently on the screen and

cope with the occasional need for repeats and the sequence-

out-ofs. QRM and contention for bandwidth would reduce

the rate still further for very rare and popular DX.

1

2.2 The DXpedition protocol changes FT8 for both the DXpedition

station (the fox) and their callers (the hounds). A single fox transmitter can generate multiple FT8

signals simultaneously, and may send messages to two stations in the same transmission (ending

one QSO and starting the next) on a single frequency, making QSOs with several hounds in parallel

on one rig and band. Fox rates may approach 400 QSOs per hour, per station!

2.3 To use DXpedition protocol as a hound (a DX chaser):

•

Install, run and configure a recent version of

WSJT-X or JTDX . Get it running properly, ideally

with CAT control of your radio using the Rig or

Fake It settings. Spend some time making normal

QSOs to familiarise yourself with FT8 operating.

If you don’t have CAT control, you will

have to QSY your Tx somewhere below

1

000 Hz manually after the fox responds

to your calls. If you don’t QSY, the fox

can’t complete the QSO with you.

Add the nominated DXpedition FT8 frequencies

to the frequency table e.g. 14.090 (not the usual FT8 frequencies!) under F2 Settings

Frequencies. Right-click the table, then insert the DXpedition FT8 frequencies. Leave the



usual FT8 frequencies alone (it’s OK to have multiple FT8 frequencies on each band - set up a

separate configuration for DXpeditions if that helps).

When the DXpedition is on the air, expand the band coverage of your waterfall ▼ to view from

2

00 to 4000 Hz e.g. using 3 Bins/Pixel and start at 200. Although your rig’s bandwidth may not

cover the entire range, with CAT control you can shift-click the waterfall to transmit anywhere

above 1000: before transmitting, the rig will automatically QSY and generate the appropriate

audio frequencies, QSYing back again afterwards. However, you may then be unknowingly

3

2

QRMing other callers if your waterfall blanks out towards the right .

32

With my K3, the waterfall blanks out just above 3500 Hz, even with the K3 data mode filter wide open at 4.0 kHz.

P a g e |54

FT8 Operating Guide

•

In WSJT-X, select Special operating activity then Hound on the F2 Settings  Advanced tab

(unless you are the fox on the DXpedition!) ▼

•

It’s easier still in JTDX : click the Hound button on the main screen ▼ then right-click it to enable

the auto-QSY Frequency Control function. It even auto-cancels when you revert to the normal

FT8 frequencies. Nice!

◄

Left click

enables

Hound mode,

then right

click for

HoundFC ▼

P a g e |55

FT8 Operating Guide

1

2.4 In DXpedition mode, a hound’s Band Activity left hand pane only shows

decodes up to 1000 Hz, in other words the fox and the hounds he is working,

unless you have selected Rx All Freqs on the main screen ►. The fox sees

them all, of course, and selects them to add them to his queue.

2.5 In DXpedition mode, most of the usual

message selectors are greyed-out ³³

,

leaving just two ► You will call the fox

with your Tx 1 message until he

responds to you, then you’ll send Tx 3

with your report until he acknowledges

it. That’s it. No RRR or 73 or custom

messages are needed from you – keep

your transmissions to the absolute

minimum so other hounds have their

chance to catch the wily fox.

1

2.6 Point your antenna towards the

DXpedition and select an appropriate

power level (typically in the region of 5 to 50 watts – neither so little that you won’t be heard, nor

so much that the fox pointedly ignores you).

1

2.7 Shift-click (WSJT-X) or right-click (JTDX ) to set your transmit frequency (the red goalpost) on a

reasonably clear column on the waterfall above 1000 Hz.

2.8 Wait patiently until you see the fox transmitting, generally on the even cycles. You may see his

single CQ call, or several signals as he makes QSOs with up to 5 hounds in parallel. Fox decodes

often include concatenated

messages like this ► Here a very

weak fox is completing a QSO

with NA7TB and (at the same

time on

a

second fox Tx

frequency), sending a report to K5EK.

1

2.9 Once you are copying the fox reliably, double-click one of his decodes to set things up and start

calling him in the normal fashion.

If you cannot copy the fox, DO NOT CALL HIM as you will simply create QRM and

aggravation. Even if by some miracle he responds to you, you won’t see his response

…

and someone else may miss out on a QSO as he tries to contact you in vain. Try

turning your beam or using another antenna. Try another band maybe. Do the

sunspot dance. Or simply wait patiently like a good DXer, watching the screen, poised

to pounce like a hawk if and when you do see decodes from him.

3

st

The Tx even/1 option is also unavailable to the hounds: foxes ALWAYS transmit on the even/1 sequences. You will normally

see lots of blobs on the odd/2ⁿ^dsequences, but hopefully only the fox on the left of the waterfall on the evens.

P a g e |56

FT8 Operating Guide

1

2.10 In DXpedition mode, a special hard-coded timer automatically disables your transmissions after 2

3

4

minutes without a response … however, in that time, the fox may have put you on the queue. If

the fox responds to you later, after your DXpedition mode timer has timed out and before you re-

start transmissions, your Tx will automatically be re-enabled to send him his report, completing

the QSO when he acknowledges it with his RR73 message back to you. Use the Tx breaks wisely.

If necessary, QSY to a nice clear Tx frequency and hope it is clear at the fox end. Adjust your power

and beam if necessary. Watch the screen. Fiddle

with the radio. Bide your time. Enjoy the

moment. Behave yourself. Be an obedient hound.

1

2.11 If the fox responds to your call with his Tx 2 message (your callsign and report), your system will

3

5

automatically QSY your Tx to a frequency below 1000 Hz to send him your Tx 3 message (both

callsigns, R and his report). If you don’t have CAT control, you should QSY manually below 1,000

Hz to make the QSO unless the DXpedition op is alert enough to complete it manually.

2.12 If for some reason a fox is transmitting on the odd/2ⁿ^dperiods, hounds

st

can use control-E to force their transmissions to the Even/1 periods

st

even though in WSJT-X the Tx even/1 option on the screen is greyed out

in DXpedition mode ► As well as not being active to select the period, it

doesn’t show the current status. Use shift-E to return to the odd/2

nd

periods, the default.

1

2.13 Your system will continue sending Tx 3 below 1000 Hz several

Having initially responded

times until the fox acknowledges receipt with his Tx 4 message

to your calls, if the fox is

(

your callsign and RR73, possibly as part of a multi-transmission

ignoring

messages,

your

Tx

3

Tx

message), concluding the QSO.

2.14 The fox will send your report up to 3 times before giving up, frequency may be busy with

logging the QSO and moving on to the next one. This happens other callers causing QRM.

automatically. So, if you don’t receive an RR73, there’s little Try manually shifting your

3

6

point continuing to transmit your report incessantly : you are Tx to a different, clear

wasting time, energy and bandwidth. Stop sending and (when frequency on the waterfall.

available) check that you are in the online log … or if you are Stay below 1000 Hz though.

desperate, try again another day, making an insurance QSO.

34

Due to a persistent WSJT-X “feature”, the WD timer value remains static in the bottom right corner of the screen in

DXpedition mode. The normal WD timer is not used. Instead a separate, secret, internal timer is hard-coded at 2 minutes (4

transmissions). When your 2 minutes baying at the fox are up, the receiving bar does not go red and display “Runaway Tx

watchdog” as it normally does with the WD timer. The Enable TX button is automatically deselected, loses its red background

and you stop transmitting. That’s it.

3

5

6

It does this intentionally to separate you from the other baying hounds. All that yapping would slow or prevent your QSO.

The fox will see your continued plaintive messages if they are decoded, and he may take pity on you, responding manually

3

by forcing through what, to him, is a duplicate QSO. However, that may mean the fox ignoring another caller who is not already

logged, so unless this is your only shot at a rare QSO (an ATNO), stop hounding the poor fox!

P a g e |57

FT8 Operating Guide

1

2.15 In Hound mode, information from decodes is not routinely sent out onto your shack network via

UDP, although once you work and log the fox, the log QSO message is broadcast as normal. The

usual stream of UDP messages resumes when you leave DXpedition mode … so after you work and

3

7

log the fox, don’t forget to de-select Hound and tune back to the normal FT8 frequencies … unless

you are hunting the fox on another band next. Take a moment to celebrate the wonders of weak-

signal digimode DXing!

2.16 MSHV has a hybrid multi-transmit mode (called “Multi Answering Auto Seq Protocol FT8"), similar

but not identical to the DXpedition fox-n-hounds mode. These are conventional FT8 QSOs except

the DX station/fox makes several at once using separate transmit frequencies. Some DX stations

have taken to running this way on the normal FT8 frequencies, causing confusion and hogging the

subband: it would be more considerate of them to shift to a different frequency.

“

FT8: Decoding is now spread over three intervals. The first starts at t = 11.8 s into an

Rx sequence and typically yields around 85% of the possible decodes for the sequence.

You therefore see most decodes much earlier than before. A second processing step

starts at 13.5 s, and the final one at 14.7 s. Overall decoding yield on crowded bands is

improved by 10% or more. (Systems with receive latency greater than 0.2 s will see

smaller improvements, but will still see many decodes earlier than before.)”

Email from Joe K1JT to the WSJT-X development reflector, May 2020

37

I recommend checking that the Hold Tx Freq option remains selected after entering and leaving DXpedition mode. Due to

an annoying little bug in WSJT-X, it is silently de-selected.

P a g e |58

FT8 Operating Guide

13 Flaws, bugs and improvements

1

3.1 Flaws or limitations in the design of FT8 and the associated

software, plus bugs and problems with our on-air operating

conventions, are coming to light. Most are trivial and can be easily

overcome or simply ignored. Some are potentially more significant

blockers, such as:

Much of this is

subjective: some of the

things I call “flaws”,

“bugs” and “issues”

others dismiss “as

designed” and “not a

problem”.

•

The handling of special callsigns .

Inconsistencies and awkwardness in the user interface,

especially in WSJT-X (more below).

•

Differences of opinion on what truly constitutes a completed, valid QSO, and on how to use FT8

for contesting.

Inconsiderate operating such as calling over the top of ongoing QSOs, rudely ignoring directed

CQ calls and messages, over-driven audio and excessive power for the path, and contention for

finite band space.

3

8

1

3.2 There are inconsistencies, limited data-entry validation and other usability issues in WSJT-X such

as:

•

The message selector buttons can be ambiguous ►

There’s no feedback to the user when entering or

editing a free-text message that goes beyond 13

characters or includes invalid characters [solved in

JTDX ].

•

Inability to toggle message settings (e.g. swapping

message Tx 4 between RRR and RR73) without also

selecting the toggled message to be sent immediately

[

solved in JTDX ].

•

Inability to change the Rx frequency while transmitting.

Decodes are appended to the Band Activity and Rx Frequency window strictly according to

when they were decoded (on the first pass then the second pass), with no ability to sort them

by frequency, call, locator, strength or time received.

•

New decodes reset the Band Activity window to the bottom, even if we were scrolling up

looking for a specific decode (the only way to lock the list is to stop decoding).

The Tx and Rx frequency-setting boxes include the static/boilerplate text “Tx”, “Rx” and “Hz”,

which makes it a bit trickier to update the numeric values: we first need to select the numbers,

being careful not to select the boilerplate text.

•

Shift-clicking F11 or F12 moves the Tx down or up in 60 Hz steps but (on my system) this stops

working after WSJT-X has been running for a while. Subsequently, those function keys move

the RX frequency in 1 Hz steps, regardless of whether I also hold shift, control or alt.

38

JTDX is not immune to issues but, in my experience, they are fewer and less annoying than those in WSJT-X.

P a g e |59

FT8 Operating Guide

•

Various auto-sequencing issues including the bouncing ball thing noted earlier and QSO

hijacking , plus possible inconsistencies in responding when someone answers our CQ with their

Tx 2 skipping Tx 1.

The log QSO pane evidently only appears if we send a free-text message containing the string

“73” … but what if I choose to end my QSOs with, say, “BIT.LY/FT8OP” (the short URL for this

very document) or “MERRY XMAS” or whatever? If I’m not on-the-ball, there’s a good chance I

will neglect to log the QSO.

•

The “Disable Tx after sending 73” option is ignored if you are using Call 1st. After logging a QSO,

remember to Enable Tx to start your next CQ.

Any change to the current Tx 5 free-text message is lost if we open and close F2 settings: it

reverts to the auto-generated plain [his call] [my call] 73 message.

In DXpedition mode, fox decodes don’t stand out on the Band Activity pane unless it is a new

DXCC country. It would be handy if decodes from the fox (i.e. sent by the callsign currently in

the DX Call box) were highlit in some way, even when he was not actually working us. This

might be useful also in non-DXpedition mode.

•

Various other minor issues (e.g. confusing colours, low-contrast sliders,

truncated screen-tips ► etc.).

1

3.3 These and other concerns, plus test findings (ideally explaining how to

reproduce bugs on demand), suggested workarounds and improvement

suggestions in general may be discussed on the WSJT reflector.

However, despite the splash screen warning message when rc/beta

versions load

If you are a UI

programmer,

please volunteer to

work on WSJT-X:

your expertise is

sorely needed!

◄

, if you are

not

programmer

a

willing to get involved in coding User

Interface changes on a multiplatform

system, be prepared for your UI-related

feedback to be ignored or robustly

rejected: essentially, UI matters are

unwelcome distractions to the team.

1

3.4 Users should be able to disable the auto-QSY CQ function intended for VHF/UHF use as it can

cause the transmitter to QSY unexpectedly, perhaps out of band. For example, imagine a station

on 1850 kHz sending “CQ 1930 AB1CDE”: if we double-click that message to respond to them, our

rigs will automatically QSY to 1930 kHz to make the QSO.

P a g e |60

FT8 Operating Guide

1

3.5 Technically, FT8 and other digimodes can be fully automated, replacing operator effort and manual

input with CPU cycles, but that is a step too far for most amateurs, as well as the team behind the

JT modes: this is, after all, a participative hobby. Watching our stations making QSOs ‘for us’

reduces us to passive observers. However, one potentially useful application involves setting up

automated stations on extremely inhospitable DX

Provided

the

licensing

and

locations such as Bouvet Island. I envisage futuristic

DXpeditioners taking robotic FT8 stations with them, to

sit silently in the corner racking-up rare DX QSOs for the

duration of the trip … and perhaps beyond ►

environmental authorities approved,

self-contained ruggedized solar-

powered FT8 robots with satellite

links for logging and control could

potentially be left behind when the

DXpeditioners depart, perhaps with

scientific research and monitoring

capabilities (like weather stations) to

justify their continued presence.

FT8 may also be useful for telematics (e.g. remotely

monitoring/controlling repeaters and beacons, tracking

vehicles) and store-and-forward email-like systems

using long-distance amateur HF radio links, rather than

VHF/UHF point-to-point, satellite or Internet links.

1

3.6 Various other enhancements to the FT8 protocol and

software have been suggested e.g.:

•

Using a bit as a flag denoting “Message continues”, allowing free-text messages to be chained

together on transmit and reassembled on receipt (JS8 uses the ~ tilde character ~ in the

message text for a similar purpose).

•

Combining the audio streams from separate antennas and receivers (diversity reception).

A simple “go back” function to un -do a QSY, instantly returning to the previous tuned frequency.

Enhancing WSJT-X’s logging and lookup capabilities .

Aside from the substantial effort required to specify, code, test, debug and document such

changes, there are other issues to consider:

•

Complexity: the more complicated the system, the more likely it is to suffer performance and

other limitations, including design flaws, bugs and operator errors.

•

Backward and forward compatibility: step-changes are problematic, hence incremental

changes are preferred … but that’s not always possible (e.g. the

At the end of the day,

change from 75 to 77-bit FT8 forced everyone to upgrade or be

the developers have the

left for dust).

final say in what gets

•

Priorities: one amateur’s enhancement is another amateur’s

drawback. It is hard to gain consensus on the few changes

actually worth progressing from the many possible approaches,

especially given the variety of applications for WSJT-X (e.g. EME

and meteor scatter on VHF/UHF, plus HF DXing).

implemented and how,

since they are the ones

doing the hard graft. It’s

their ball: we’re just

kicking it about.

Take-home lessons for DXpeditioners intending to use FT8:

1

2

) Request a standard, conventional, short DX callsign if possible; and

) Try-out the current release of WSJT-X using your (likely) DX call and get

familiar with running DXpedition mode as a fox well before setting off.

P a g e |61

FT8 Operating Guide

14 Close and acknowledgements

1

4.1 Remember, it’s only a hobby. Most of the issues with FT8 operating are not due to malice but

ordinary hams like you and me, exploring the mode and picking up tricks as we go. We make

mistakes. We get things wrong. We experiment. We try. We learn. We enjoy ourselves and help

each other out. Slack needs to be cut. Stay cool. Chill bro’!

1

4.2 Although my name is on the front, this document is largely the product of the HF DX community.

Please join me in thanking the numerous amateurs who have kindly contributed ideas, comments

and tips, particularly of course the professors (Steven Franke, K9AN and Joe Taylor, K1JT ) who gave

us the mode, plus the other WSJT-X developers and long-suffering support crew on the WSJT

reflectors (Bill Somerville, G4WJS in particular). I have collated, interpreted and expanded upon

their inputs, drawing heavily on their inspiration and information. I take full responsibility for all

my mistakes … and express my sincere thanks for those of you who put me straight !

1

4.3 Your feedback on this document, such as corrections, responses/challenges, improvement

suggestions and further tips, are very welcome. Please email me: Gary@isect.com I will try to

maintain the online living version of this document on my website (www.G4iFB.com ) as time and

energy permits. No promises though: I have a job to do and given the choice I’d rather be flapping

my trusty Bencher paddle than bashing the keyboard.

◄

I am part of the merry band that developed and

promotes the DX Code of Conduct . We know it is

imperfect but the situation would be even worse

without it! Something had to be done about

declining operating standards, so we did …

something. So what have you done lately?

If you c an stomach any more of my

writi ng, you might enjoy the

FOC Guide to Morse Code Proficiency ►

Find out more about me on

G4IFB.com and QRZ.com or

catch me on the air

P a g e |62

FT8 Operating Guide

Appendix A: About FT8

A limited amount of technical information about FT8 is available on the web, such as this brief outline

when FT8 was first announced with the release of WSJT-X v1.8.0 Release Candidate 1 (I have added a few

links for those who, like me, feel the urge to explore further):

WSJT-X Version 1.8.0 includes a new mode called FT8, developed by K9AN and K1JT . The mode

name "FT8" stands for "Franke and Taylor, 8-FSK modulation". FT8 uses 15-second T/R sequences

and provides 50% or better decoding probability down to -20 dB on an AWGN channel. An auto-

sequencing facility includes an option to respond automatically to the first decoded reply to your

CQ. FT8 QSOs are 4 times faster than those made with JT65 or JT9 . FT8 is an excellent mode for

HF DXing and for situations like multi-hop Es on 6 meters, where deep QSB may make fast and

reliable completion of QSOs desirable.

Some important characteristics of FT8:

•

T/R sequence length: 15 s

Message length: 75 bits + 12-bit CRC

FEC code: LDPC (174,87)

Modulation: 8 -FSK , tone spacing 6.25 Hz

Constant-envelope waveform

Occupied bandwidth: 50 Hz

Synchronization: 7x7 Costas arrays at start, middle, and end

Transmission duration: 79*1920/12000 = 12.64 s

Decoding threshold: -20 dB; several dB lower with AP decoding

Multi-decoder finds and decodes all FT8 signals in passband

Optional auto-sequencing and auto-reply to a CQ response

Operational behavior similar to JT9, JT65

Two further definitive sources of information on FT8 are the WSJT-X help file (provided with the program)

and a brace of articles in QST written by Joe Taylor, K1JT, Steve Franke, K9AN, and Bill Somerville, G4WJS:

“

Work the World with WSJT-X, Part 1: Operating Capabilities ” – QST October 2017, pages 30-36 – a

general introduction to the digital modes supported by WSJT-X.

Work the World with WSJT-X, Part 2: Codes, Modes, and Cooperative Software Development ” – QST

“

November 2017, pages 34-39 – dips further into the mathematics, Forward Error Correction etc.

An excellent presentation by Joe Taylor explains the history behind WSJT-X and FT8.

One further source is the source itself, in other words the program source code for WSJT-X and the

associated documentation, generously made freely available through a Creative Commons license in

order to encourage widespread uptake and continued development of the digital modes.

Finally, Joe maintains a set of references at www.physics.princeton.edu/pulsar/K1JT/refs.html

“

The popularity of FT8 on HF is largely a happy accident in that it fulfilled a latent

frustration of many potential users of WSJT-X with the slow rate of QSOs using 1 minute

T/R periods. Clearly that frustrated group of users did not require the greater sensitivity

of JT65 or JT9 and once the level activity grew greatly the opportunities for many QSOs,

even with limited equipment, caused a near exponential growth since launch.”

[

Bill Somerville, G4WJS]

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FT8 Operating Guide

Appendix B: JS8 for weak signal text chat

JS8 (Jordan Sherer-designed MSK-8) is an experimental digimode inspired by

FT8 shortly after its release in 2017, designed and then implemented in

software by developer Jordan Sherer (KN4CRD) during 2018.

The JS8Call software

supporting JS8 mode

was originally known

as FT8CALL.

JS8 is derived from FT8 and freely shared in accordance with the FT8 open

source license, in the best traditions of amateur radio.

It applies FT8-style message encoding and modulation to longer

“

JS8Call has

a

directed

messages, in effect allowing senders to transmit across adjacent time

slots instead of the usual 15 second alternating transmit-receive

sequence. The tilde character denotes the end of a message sequence.

calling protocol laid over top

the base RF transport to

support free-form and

directed message passing.

Hence JS8 + Directed Calling

7

5-bit JS8 messages cannot be decoded by 77-bit FT8 software. They

use different sub-bands (e.g. 7078 and 14078 kHz).

Re the message length, “longer” is relative. This is still a block-mode = JS8Call … The mode is: JS8.

system compressing and sending an entire block of information (several The app is: JS8Call.”

characters) at a time, unlike say RTTY, PSK or CW where each individual

character is encoded separately then sent, received and decoded.

JS8Call User Guide

As of JS8Call version 2.1, four speeds are available in JS8:

•

Slow: 30 second frames, 25 Hz bandwidth, 3.125 baud (~3½ WPM) decoding down to -28dB.

Normal: 15 second frames, 50 Hz bandwidth, 6.25 baud (~7½ WPM) decoding down to -24dB.

Fast: 10 second frames, 80 Hz bandwidth, 10 baud (~12 WPM) decoding down to -20dB.

Turbo: 6 second frames, 160Hz bandwidth, 20 baud (~24 WPM) decoding down to -18dB.

The FT8-style message integrity controls built-in to JS8 make it

suitable for applications such as leisurely chats over weak signal

paths, emergency comms using solar or wind powered QRP

stations with temporary/inefficient antennas, and automated

beacon-type stations broadcasting sensor data. It makes efficient

use of even low-quality RF bandwidth.

“

The idea with JS8Call is to take the

robustness of FT8 mode and layer

on a messaging and network

protocol

communication on HF with a

keyboard-to-keyboard interface.

JS8Call is heavily inspired by WSJT-

X, Fldigi, and FSQCall and would not

exist without the hard work and

dedication of the many developers

in the amateur radio community.”

for

weak

signal

For more information, see:

•

The JS8Call website

Jordan’s original design specification

The current (maintained, updated) User Guide for JS8Call

The IOgroups user and tech support forum for JS8Call

JS8Call.com

“JS8Call is a derivative of the WSJT-X application, restructured and

redesigned for keyboard-to-keyboard message passing.”

JS8Call IOgroups description

P a g e |64

FT8 Operating Guide

Appendix C: JTDX

Personally, I prefer JTDX over WSJT-X for FT8 HF DXing. The programs are similar enough that swapping

between them is easy with a shallow learning-curve. I find the JTDX user interface more intuitive, less

awkward and stressful, easier and more efficient in practice than WSJT-X. YMMV.

•

The main screen layout ▲ moves the settings to the righthand side leaving more vertical space on

the left for up to 50 ‘band activity’ decodes, showing most if not all of the decodes from the last

period even on a very busy HF band. There is less space for messages to/from me in the right ‘Rx

frequency’ pane but still plenty enough in practice for the present and usually the previous QSO.

•

I can left click the waterfall to move the dead green Rx goalposts there, or right click to move the red

Tx goalposts. That is intuitive and one-handed, with no need to press a keyboard key while clicking

the mouse.

We have the option to shift the timestamps to the right of the waterfall or hide them – useful as they

can obscure weak DX fox signals. Also the waterfall sliders have labels and values, making it easier to

try out changes and if necessary return to known good settings. JTDX is getting even better by the

week!

P a g e |65

FT8 Operating Guide

•

My even/odd Tx slot setting button is blue or yellow, respectively, and the adjacent clock uses the

same colours depending on the time, making it easy to determine whether I would be

transmitting or listening at any point: I transmit when the colours match.

Having selected ‘Prompt me to log QSO’ under F2 Settings  Reporting tab, JTDX displays

the logging pane at the end of a QSO, waiting patiently for me to check it and click “Log

QSO”. That click also re-enables Tx and selects Tx 6, my CQ message, making it easier to

continue CQing, unless I have selected “1 QSO” on the main menu ► That’s a single-shot

option meaning ‘remain in receive after completing the present QSO’. It’s an easy way

to conclude a session and slip away for a cup of tea.

•

If I select ‘Enable automatic logging of QSO’ under F2 Settings  Reporting ▲ my QSOs are logged

automatically on completion, giving me no chance to check and modify the log entry (e.g. noting the

power I am using). Even with that option selected, JTDX deliberately does not recommence CQing

after a QSO is completed and logged, as that would make the operator redundant.

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FT8 Operating Guide

•

When I respond to someone else’s CQ, there is an option to stop my transmissions automatically if

he responds to someone else … which reduces needless QRM, reduces my power bill and most

importantly gives me the chance to check that my transmit frequency appears clear when I would

otherwise have been transmitting. [WSJT-X only stops my simplex transmissions.] If for some reason

I want to hound someone, calling them repeatedly, I simply click the Hound button … but that setting

also stops me sending a custom 73 message.

•

The PC beeps when people call me, using the Windows default output sound card. A handy audio

cue, that, if I am busy working on another screen.

When I am CQing, the auto-sequencer can be

Better autosequencing is a distinct

configured to auto-respond to the most distant caller

advantage of JTDX over WSJT-X for DXers

instead of simply the first caller decoded. I guess it

uses grid squares to calculate the distance, otherwise

the country identified by the prefix. There are other

autosequence options too.

like me … but it still makes mistakes, so

keep an eye on it anyway.

•

Using a new control on the waterfall, I can shift the timestamp from the left to the right edge of the

waterfall, or turn it off completely, making it easier to see feint traces of DX foxes on the left.

I can easily generate directional CQs targeting a specific country or continent, and more importantly

the autoresponder can be set to ignore callers not in my target area, if I choose to do so. [I’m not

sure it handles custom CQs though: it only accepts 1 or 2 letters in the entry box].

•

When someone responds to my CQ call but their response decodes late (after I have started my next

CQ call), the autoresponder automatically flips to sending them their report and erases the partially-

transmitted CQ message from my screen, making it easier to figure out what messages were sent.

Logger32 communicates bidirectionally with JTDX ³⁹via UDP

After clicking someone’s

messages . I can display all the stations decoded in JTDX on

Logger32’s “UDP bandmap”, with any new ones highlighted for me

in the same colours as DXcluster and RBN spots on the conventional

bandmaps ◄. If I click a decoded FT8

callsign

on the UDP

bandmap, Logger32 waits

politely until it has received a

further message from him

before telling JTDX to call

him. With minimal user

feedback (just a box around

the call on the bandmap as it

waits to call the selected

station), the pregnant pause

can be disconcerting but be

patient. Trust me, it works …

eventually, usually.

callsign on the UDP bandmap, JTDX

will call him when appropriate (either

when he next CQs or when he sends

his 73 or RR73 message at the end of a

QSO, according to the bandmap config

settings). If he doesn’t immediately

respond to my call, I can simply wait

patiently to call him again, try calling

another wanted station in the same

way, start CQing, or give up.

39

It also communicates with WSJT-X via UDP, with minor differences e.g. WSJT-X only lets Logger32 respond to CQs.

P a g e |67

FT8 Operating Guide

•

Logger32 can optionally also display another bandmap-type thing

showing only the stations currently calling me, with their entries

highlighted in the normal manner – handy when I’m being called by

several stations at the same time, trying to decide which one to respond

to first. In the example ► I’m being called by LY1CZ who I have

contacted before (hence the X) plus DJ0YI in grid JN48 that I haven’t

worked yet on this band (hence the blue highlighting). While it would be

good to contact LY1CZ again, I would probably respond to the German

first by double-clicking a decode from him in the Rx frequency pane on

JTDX, letting the autosequencer take us through the conventional QSO

sequence. Meanwhile, if anyone else calls me during our QSO, their call

will also appear as if by magic on the calling me bandmap so I can get

ready to respond to one of the callers in the same manner – going for

the highlighted ones first, generally.

•

The JTDX lower status line shows useful info. It pays to keep an eye on things. Here are three

snapshots showing the 8 fields at different stages of a QSO ▼

1

2

This field normally shows the message you are transmitting (yellow) or ‘Receiving’ (green). The red

warning message appears when the watchdog counts down to zero and your transmissions have

ceased.

If you are monitoring an active FT8 subband and

see plenty of FT8 signal blobs on the waterfall

but no decodes, check that you haven’t

accidentally selected a different mode. Doh!

The mode: JTDX supports FT8 and a few other

HF JT-type digimodes (JT9 & JT65, T10 and

WSPR-2 ).

3

4

The message you transmitted last.

Watchdog timer counting down the minutes remaining. Click anywhere in the program’s main

window, or log a QSO, to reset it to the starting value defined in F2 Settings  General tab.

5

6

Shows each over ticking away the 15 seconds with a coloured progress bar. Red = transmitting.

Green = receiving.

The callsign of the station logged most recently. Handy if, like me, you sometimes get distracted and

forget whether you have logged someone.

7

8

The date in UTC (I presume).

How many QSOs you have logged on this mode, in this program, under your current callsign, in the

current ADIF log file.

P a g e |68

FT8 Operating Guide

•

JTDX supports contacting foxes with a simple click or right-click on the Hound button on the main

screen ► Left-click the

button to make brief

split QSOs without

QSYing below 1000 Hz

(

e.g. when working a

DX station using

MSHV’s multi-transmit

function), then right-

click if you want your

rig to QSY below 1000

automatically

the DX responds to you

the button then shows HoundFC meaning hound with

Frequency Control). The auto-QSY function is disabled and

cannot be selected on the normal FT8 frequencies since DX

stations should not be using fox-n-hounds or indeed multi-

transmit mode in the normal FT8 subbands.

when

(

Pileups clog-up the normal subband.

Spare a thought for those who are

not presently trying to work the DX.

Please take your pileup elsewhere!

•

The Hound button also lets us hound (as in pester) DX

stations, calling them persistently even as they call and contact other stations. There are situations

where that may be justified, but please consider the effect continuous calling has both on the DX and

on other band users. If your calls are going unheeded, it may be that your Tx frequency is busy at the

DX end. If you are so selfish as to be calling the DX simplex, your calls may well cause QRM to the

stations he is calling and working. Play nicely, please.

Ever wondered about the little

symbols that appear in some

decodes?

In JTDX, the symbols

between the audio frequency and the

decodes message denotes the specific

digimode: a tilde (~) means FT8, and a

colon (:) means FT4. Here ► I was on

FT8 until 00:09:06, then I changed to

FT4 … I guess there are other symbols

for the other digimodes but you’ll

have to figure them out for yourself.

The ‘help’ for JTDX is vestigial and 2

years out of date so it took some

Googling and checking to figure this

much out about the symbols. It’s a

never-ending challenge to document

this stuff!

P a g e |69

FT8 Operating Guide

•

There are more symbols at the left edge of the country area of the

band activity window ►. I think a solid (filled) bullet point means the

sender is on LoTW; an asterisk means decoding used a hint i.e. a priori

info from previous messages; an empty (unfilled) bullet means it used

a hint and the user is on LoTW; no symbol presumably means he’s

neither a LoTW user nor was a hint used … but I’m not entirely sure

about this.

In WSJT-X, the symbols may differ. It’s left as an exercise

for you, dear reader, to figure out what they all mean.

There are fewer bugs and flaws in JTDX than WSJT-X but some issues remain e.g.:

•

In an early version, the main screen’s radio message-selector buttons used to be clickable during a

transmission, allowing us to select the next message after the present one is gone, manually

overriding the autosequencer. For some reason, that handy trick no longer works. We can still click

the Tx buttons to send a given message now, but if we do that during a transmission, it changes the

message currently being sent which can easily result in a corrupted, undecodable message unless we

are careful/lucky with the timing.

•

During QSOs, JTDX quite often replaces my manually-typed custom 73 message with the boring auto-

generated default (<his call> <my call> 73), too late for me to re-type the message I wanted to send.

This usually happens when the autosequencer has to repeat a message, so I guess it is an annoying

little ‘feature’ in the autosequence logic.

•

Unless my custom Tx 5 message includes the magic string “73”, the QSO is not automatically logged,

nor am I prompted to log it. It just quietly disappears into the ether.

If I fiddle with the settings using F2, when I exit the settings my transmission is aborted and the callsign

of whoever I’m working is cleared. Too bad. Unless I remember their callsign they’re toast.

Selecting or deselecting the RRR message during a QSO doesn’t simply change the contents of Tx 4 as

expected: it also appears to select a different message to send next, for no apparent reason, but

luckily the autosequencer generally picks the correct one anyway.

•

With Hound selected in order to hound a selected DX station, double-clicking a decoded message

from someone else has no effect. I think this may be intentional – it’s certainly a handy reminder to

deselect Hound.

Also, while in Hound mode, we can’t send custom 73 messages. I accept that the primary reason for

fox-n-hounds is to make QSOs as efficiently as possible so 73 messages are superfluous but

occasionally there are genuine reasons for hounds to want to send custom messages to the fox – for

example “LONG PATH”, “TRY CW”, “ZL CALLING”, “CHK SMS” or <ahem> “WHEN 160”. The

workaround is simply to deselect Hound mode.

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FT8 Operating Guide

Appendix D: FT8 under the hood

FT8 does not simply encode and transmit our messages character-by-character (in the same way as, say,

CW or RTTY or PSK). The entire message is encoded first, as a block, using a clever algorithm that

compresses the message down to 77 bits which are then transmitted

digitally along with error correction bits through our radios and the FT4 transmits the same 77-bit

ether, taking 12.6 seconds. On the receiving end, the process happens messages

plus

error

in reverse: the digital bits are dragged kicking-and-screaming from the correction bits at roughly

ether, error-corrected then expanded back into those human- twice the rate and bandwidth

readable and often actionable message that we read and double-click … which halves the sensitivity

on – hopefully within the remaining 2.4 seconds before the next (-3.2 dB in fact).

transmission period begins.

The ‘compression down to 77 bits’ on transmit, and corresponding expansion on receive, introduces hard

constraints on the amount and nature of information that can be passed using FT8. Under the covers, the

software uses algorithms for compression and expansion, algorithms that are specified as an integral part

of the FT8 protocol. They are designed to work in a fixed, predefined, mechanistic (=algorithmic!) way,

squeezing as much useful information as possible into the few bits exchanged in each over. In order to

do that, they make some simplifications which, in turn, create the constraints that we live with.

Take a look at section 17 of the WSJT-X

Each character in a 13-character free message is converted

to a number, then those numbers are multiplied together

forming a large integer of 71 binary bits. Standard messages

consist of two 28-bit fields normally used for callsigns and a

online user guide for more details about

the protocol, or study The FT4 and FT8

Communications Protocols article by

Steve Franke, Bill Somerville and Joe

Taylor in QEX July/August 2020.

1

5-bit field for a grid locator, report, acknowledgment, or

73” message, also totalling 71 bits. Six message-type bits

“

are appended, giving 77 bits. These are the precious

information payload. All the remaining bits in transmitted

FT8 and FT4 messages are required for error-correction

purposes, enabling the payload to be reliably communicated

over a noisy radio channel. The Low Density Parity Check is

assembled thus:

•

A 14-bit Cyclic Redundancy Check is calculated on the 77

bits and appended, giving 91 bits.

Next an 83-bit parity code is calculated and appended,

giving 174 bits.

The 174 bits are grouped into 58 chunks of three bits

each, which are then Gray coded .

Symbols are now assembled from a 7-chunk Costas array +

the first 29 Gray-coded chunks + the 7 Costas + the

remaining 29 Gray-coded chunks + the 7 Costas , resulting in

7

9 symbols for transmission. Those Costas arrays (“sync

vectors”) sent at the start, middle and end of each FT8

message are used to synchronize the receiver to the sender

such that bits can be reliably timed within the transmissions.

P a g e |71

FT8 Operating Guide

th

Notice there are just 28 bits available to communicate a conventional callsign. 28 bits gives 2 (the 28

2

8

power of 2) possible values, which in decimal means a little under 270 million possible callsigns. Using

the algorithm defined in the protocol, that is more than sufficient

to code all the normal, conventional, old-style, everyday, standard 9LY1JM was a classic example – an

callsigns currently in use across the world, each one coding to a unusual callsign allocated for a

unique digital value … but 28 bits is not enough for all the weird DXpedition. That “Y” in the prefix

and wonderful special event calls that are increasingly issued. The meant it would not fit into the 28

prefix parts of our calls are defined quite narrowly in the ITU bits allowed for a conventional call

regulations and by general convention, but the suffix parts are without being hashed …. but bugs

more flexible, giving too many possibilities to squeeze into the in the autosequencing in WSJT-X

available 28 bits. Any HF DXer will surely have come across some messed up the fox-and-hounds

of them on air, on the legacy modes – VK novice calls, for example, DXpedition protocol with a hashed

have 4-character suffixes starting with “F”. Self-assigned suffixes callsign. Live-n-learn.

are another example: when they were first used on-air, many of us

wondered whether /LH indicated the lighthouse stations were actually in Norway! I’ve worked and logged

stations using /QRP, /MM, /M, /P, /A, /AM, /PP, /R and other curious variants, some made up on the spot,

some probably not in conformance with the op’s license, as well as the location-variant suffixes such as

/

VE2 and CEPT prefixes such as P4/.

The same consideration applies to the 4-character

Maidenhead grid squares communicated with 15 digital

bits. 15 bits is more than adequate for grid square

references comprised of two Latin letters and two decimal

digits but is not enough to code all possible combinations

of four letters or numerals, which would require at least

Clearly, there’s a lot of processing going

on when FT8 signals are received and

reasonably fast

decoded hence

a

computer is needed. It’s not just the raw

CPU speed that matters though, as the

captured audio is written to disk before

processing: a slow disk, or contention

caused by other software such as antivirus

and backup programs, can cause delays

that result in no decodes being displayed

after some if not all overs. Network delays

may also cause problems e.g. if you elect

3

2

6x36x36x36 values or 1,679,616 in decimal, more than

20

… in other words FT8 falls 3 bits short. That said, the

particular grid RR73 is exceptionally interpreted by the

software as a message, not a grid. If an intrepid sailor ever

activates that grid square on FT8, things could get

interesting.

6

Six message-type bits cater for 2 (decimal 64) distinct to send decodes to PSK Reporter.

types of message. Currently, the following message types

are in use:

1

2

3

4

5

6

7

8

9

. Tx1 initial call with 4-character grid locator e.g. K1JT ZL2IFB RF80

. Tx2 response to a caller with signed 2-digit signal report e.g. K1JT ZL2IFB -05

. Tx3 acknowledging the received report and returning one e.g. K1JT ZL2IFB R-05

. Tx4 all received message e.g. K1JT ZL2IFB RRR

. Tx5 free text message, normally a 73 e.g. K1JT ZL2IFB 73

. Tx6 CQ message e.g. CQ ZL2IFB RF80

. Message contains a hashed non-standard callsign

. NA VHF contest exchange

. EU VHF contest exchange

P a g e |72

FT8 Operating Guide

1

0. ARRL RTTY Roundup exchange

1. ARRL Field Day exchange

There are enough bits for 51

additional message types.

Contact Joe Taylor and team if

you intend to define and use

additional message types.

2. DXpedition (fox-n-hounds) mode

3. Telemetry: the 71-bit payload contains arbitrary data

4-64. Not currently used … ►

The FT8 modulation scheme is 8-FSK i.e. an 8-bit transmission using 8 different audio tones separated by

just 6.25 Hz, giving an overall transmission bandwidth under optimal conditions of 50 Hz.

“

FSK in general is chosen because it allows the use of constant

FT8 uses Gaussian FSK (GFSK).

Rather than sharp transitions

between FSK tones, Gaussian

shaping is applied to smooth

the transitions, reducing

unwanted sidebands bringing

the signal closer to the

amplitude and near continuous phase signals, as such linear RF

stages are not necessary this making virtually any transmitter

suitable. FSK signals are inherently narrow without having to

apply complicated pre-modulation filtering. They are also

relatively easy to analyse in the frequency domain within a

decoder routine. Basic characteristics that have to be designed

are bandwidth (increases with greater N in N-FSK) vs. higher

symbol rates (increases with greater N in N-FSK). Given the typical

frequency stability and propagation stability on the bands

targeted, 8-FSK turns out to be a good choice for a modulation

bandwidth around 50 Hz for 15s T/R periods and the alphabet, and

symbol rate required for WSJT-X style QSO messages plus parity

optimal bandwidth.

The

amount of smoothing trades-

off narrower transmitted

bandwidth against reduced

decodability.

Plain FSK and even GFSK are

“

Given the decoded message we regenerate the transmitted

straightforward

and

waveform and use that as a reference to derive the time-varying,

complex, gain function that describes the channel. We use this to

reconstruct a (nearly) noiseless version of the received signal’s

waveform that includes the channel-induced amplitude fading and

phase-variation. The reconstructed signal is subtracted from the

received data, enabling us to uncover weaker signals that occupy the

same frequency slot as the subtracted strong signal. These weaker

signals can often be decoded on a second decoding pass, after the

stronger signals have been subtracted.” [Steve Franke, K9AN]

conventional: what makes

FT8 special is the clever way

the

software

makes

additional passes through the

captured

mathematically

audio,

removing

reconstructed signals a layer

at a time to reveal weaker

signals beneath ► Cunning!

P a g e |73

FT8 Operating Guide

Appendix E: FT8 logging and lookups

WSJT-X and derivative programs log QSOs using the ADIF XML standard. Almost all logging software can

import ADIF log files, hence it is possible to merge your digimode QSOs made and logged in WSJT-X etc.

with your legacy mode QSOs logged in programs such as Logger32, Ham Radio Deluxe, AClog, Log4OM,

DXlab, N1MM+ and many others including online logs such as LoTW, QRZ.com and eQSL, by importing the

ADIF. However, there are drawbacks to this approach:

•

A few logging programs make a hash of importing ADIF files, for example misinterpreting some of the

standard fields. Fortunately, this is a rare problem, and the basic QSO data (at least) generally makes

it through unscathed. Issues tend to arise whenever new ADIF standards are implemented, as it takes

time and effort to interpret the standard and update the software accordingly.

•

Importing an ADIF log is generally a manual, asynchronous activity: we have to stop logging digimode

QSOs for a while, open the logging program, run the ADIF import function to update our log, deal

with any options and errors, and then resume our digimode activities.

It is error-prone e.g. forgetting to do the import, importing into different logs by mistake, and

importing the same ADIF file into the same log more than once, potentially creating duplicate log

entries (unless the logging program ADIF import function automatically spots and skips dupes).

Real-time log updating is a better approach, where capable logging programs receive and merge digimode

QSO details broadcast by WSJT-X or JTDX as TCP or UDP network datagrams whenever we complete and

log an FT8 QSO.

Tighter integration of the digimode and logging software extends the possibilities. Bidirectional UDP

connections between the digimode engine and logging program make it possible, for example, to lookup

any previously-logged QSOs with a station we are contacting on FT8, showing details such as the

operator’s name and QTH, perhaps displaying their QRZ.com page and email address for good measure.

For DXers, it enables “new ones” to be highlighted as they appear on the decodes, according to how we

define “new ones” e.g. new grids, DXCC countries, zones, prefixes, club members, LoTW users, states etc.,

either all-time, just this year or month or contest, just on this band or mode, other criteria, or some

combination of the above.

WSJT-X is unlikely ever to be developed into a fully-fledged logging and awards-tracking program: the

team’s prime focus is on the coding, communication and decoding of weak signals using various

digimodes, not logging – and fair enough, they are doing a great job with that. More likely is that logging

programs will be adapted to do the digimode stuff, perhaps calling on WSJT-X or the coding and decoding

engines to do so in much the same way that some logging programs already call MMVARI or MMTTY,

through their own internal program functions, or using shared library functions to implement an FT8

modem.

Meanwhile, enterprising programmers have developed utilities

to plug some of the gaps, with JTalert being top of the heap.

JTalert uses the decodes and logged QSOs from WSJT-X to

highlight new ones (maintaining an internal HamApps database)

and pass logged QSOs through to other logging programs. It acts

as a middle-man with benefits.

I gather that JTalert can pass each

FT8 QSO as it is logged in WSJT or

JTDX to DXkeeper which can, in

turn, send on the info automatically

to TQSL to update LoTW. Cool!

To upload your FT8 QSOs to LoTW you need the TQSL program along with a digital certificate, both from

ARRL, confirming that you are duly licensed to use your callsign. If you don’t already have those, start

here .

P a g e |74

FT8 Operating Guide

The minimalist approach is to use the logging

The ADIF log file grows bigger with each new QSO

but TQSL maintains its own internal list of QSOs

previously signed and uploaded, and by default it

automatically skips those QSOs, only signing and

uploading any new ones since the last

run. Therefore, there’s no need to worry about

separating out the recent QSOs: simply pass the

entire ADIF through TQSL each time. The whole

process is painless and typically takes less than a

minute. You’ll soon get the hang of it.

facility built-in to WSJT-X (or JTDX or MSHV or

whatever): when you complete and log an FT8

contact, it appends a QSO record to the

wsjtx_log.adi (ADIF) file in the directory

%LocalAppData%\WSJT-X. You can sign and

upload that ADIF file to LoTW manually using TQSL

as often as you like: as an active DXer I sign and

upload the latest QSOs once or twice a day, others

may do it weekly, monthly or ‘whenever’.

If you use one or more separate logging programs,

it’s a good idea to pull all your QSOs (on FT8, JT9, CW, SSB or whatever, made by regular DXing or

contesting) into one consolidated log, then generate, sign and upload an ADIF file from the logging

program. Having one consolidated log makes it simpler to search for all previous QSOs with someone,

and generate statistics such as the total number of DXCC countries you have worked. Most logging

programs also let you download and save the confirmations from LoTW and input details of any QSL cards

you receive, updating the relevant QSOs to show they have been confirmed. When you have enough

confirmations, you can apply for awards such as DXCC.

◄

JTSummary was ⁴⁰a handy

little utility by Aki JA1NLX that

analysed an ADIF log to

determine the number of QSOs

made and confirmed on various

modes.

Of the ~118k QSOs in my log, I’ve

made ~33k FT8 QSOs in over 230

DXCC countries. Nearly three-

quarters of the FT8 QSOs are

confirmed, compared to about

6

0% of my CW and SSB QSOs.

Digimode QSOs require

a

computer, hence it is more likely

that digimode QSOs will be

logged and confirmed on LoTW

than legacy mode QSOs.

JTSummary also let me graph

the digimode statistics by bands,

modes and continents. Neat!

Thanks Aki!

40

JTsummary is no longer supported by Aki but Google may find you a copy online: look for the last version 1.28.

P a g e |75

FT8 Operating Guide

Appendix F: Contesting with WSJT-X

Both FT8 and FT4 can be used to exchange (some) contest information such as

sections and serial numbers using specific message types, in addition to the normal

QSO information. Contest organizers may allow or disallow FT4 and FT8 in their

events, possibly defining separate categories: check the rules!

JTDX does not

yet] support

FT8 contesting

[

To enable contest mode

in WSJT-X, go to F2

Settings  Advanced,

select

the

Special

operating activity then

select the relevant (or

closest available!) contest

type ►.

Enter the

exchange you should be

sending e.g. your field day

section code or ‘DX’. This

text is automatically

included in your outgoing

exchange message, and is

logged on receipt from

other participants.

Talking of logging, in

contest mode WSJT-X

generates

a plaintext

column-aligned Cabrillo

format contest log in

addition to the usual

ADIF log and UDP or TCP

broadcasts onto your

shack network … which

in turn enables contesting software such as N1MM+ to support FT8 contests, with all the advantages of

multiplier tracking and dupe-checking etc.

Check the contest rules for suggested or permitted

frequencies. It’s a good idea to define them in WSJT-

X’s frequencies table so they appear on the band

selector.

◄

If you set up a separate WSJT-X configuration for

contesting, you’ll avoid cluttering-up your normal

everyday settings. You can preload a specific

configuration when launching WSJT-X using the -c

command line parameter (see the F1 help for

details), or simply select it from the menu which

closes and relaunches the program for you.

P a g e |76

FT8 Operating Guide

In contest mode, the main WSJT-X window and operation is the same as always, with selector buttons for

the next message and Enable Tx to start transmitting on the next applicable slot ▼

All the usual FT8 operating and avoidance tactics apply to contests:

•

Watch and if necessary adjust your audio levels on receive and transmit to stay in

the green zone, avoiding the red.

Use the

normal FT8

subbbands,

other modes

or the WARC

bands to

avoid FT8

and FT4

contests.

•

Try not to transmit on a busy frequency.

Keep your power down to avoid causing receiver overload and nasty red blobs on

waterfalls at the other end.

•

Chase down bonus points or multipliers according to the contest rules, avoiding

disappointment.

Study and comply with the contest rules to avoid disqualification.

P a g e |77

FT8 Operating Guide

Appendix G: Picking FT8 cherries with Logger32

Most of the time, there are plenty of stations active on FT8 on the bands I’m using. With my ZL prefix, I

seldom need to CQ for long before someone responds … and that suits me fine. Sometimes, though, when

my CQs are going unheeded, it’s time to change tactics by picking out and calling other stations.

4

1

So who shall I call? As an HF DXer, these are my priorities from the top down :

•

An All -Time New One i.e. a DXCC country that I have never worked before, not ever on any band or

mode. For me, these are the ripest, reddest, sweetest, most ‘needed’ cherries of all, and as such I’m

willing to invest a lot of effort to pluck them.

•

A DXCC country that I have worked before but don’t yet have confirmed on any band or mode.

A new DXCC country for me on this band.

Someone I have just contacted and logged (are they calling back to correct something, tell me

something or still trying to complete the QSO?).

•

A new DXCC country on any digimode.

A new DXCC country on FT8.

A DXCC country that I have worked before but don’t yet have confirmed on this band.

A DXCC country that I have worked before but don’t yet have confirmed on any digimode.

A DXCC country that I have worked before but don’t yet have confirmed on FT8.

An old friend whose callsign I recognise, especially if we haven’t caught up in a while.

A DXpedition to some exotic part of the world, especially to a rare zone or grid.

An IOTA, SOTA, WFF or special event station that catches my eye e.g. a new IOTA for me.

Anyone on the Far Side, or who I think might be coming in via the long path.

Any other IOTA, SOTA or special event station.

A QRPer or anyone with a weak trace on the waterfall and low signal-to-noise metric.

Any novice or foundation-class newbie callsign that I recognise as such.

Anyone with an unusual prefix or suffix.

Those who call me off-frequency/split, avoiding the unsightly simplex red blob.

Anyone else. Anyone at all, including people I have worked several times already (within reason!).

That’s a lot to figure out, in a hurry, when I’m scanning through each batch of decoded message, but

luckily help is at hand. For a start WSJT-X and JTDX can highlight new ones on FT8 as a result of reading

their ADIF log files into memory as either program launches. The highlighting is basic and easily messed

up by me carelessly renaming or deleting the ADIF files, or meddling with the colours.

I believe JTAlert improves the highlighting … but I don’t use it so that’s all I have to say on that. Sorry.

Logging programs that interoperate with WSJT-X or JTDX increase the possibilities, for example

distinguishing ATNOs (All Time New Ones) from those we have worked on other modes, not yet on FT8,

and determine whether previously-logged QSOs have or have not been confirmed and verified for award

41

Your priorities are probably different to mine. I’m listing mine simply to point out the complexity involved, not to claim that

my priorities are any better than yours. We’re all individual, a.k.a. ‘special’.

P a g e |78

FT8 Operating Guide

purposes. Logger32 by Bob K4CY, for example, can display a “UDP BandMap” conceptually and graphically

similar to Logger32’s bandmaps for DXcluster and RBN DX spots, showing

callsigns decoded on FT8 ► The bold red callsigns are stations who have

called CQ, while the timid blue ones have responded to others’ CQ calls.

Grid squares sent by some of the stations are highlighted with background

colours according to whether they are new ones.

◀

Logger32 gives us

lots of options to

customize the

highlighting rules and

colours, using

Config/Appearance

/

Highlight colours on

the UDP bandmap

top line menu.

Your system will of

course look different

to these example

images unless you

happen to choose

the same options

and colours as me.

Logger32 supports semi-automatic DXing: we can select interesting stations

on the UDP band map, then sit back and watch developments. If our chosen

station completes a QSO or calls CQ, Logger32 sends a UDP message telling

WSJT-X or JTDX to call him. If he starts another QSO with someone else,

Logger32 quietly bides its time until it is appropriate to give him another

call … like this

◄

When I first

noticed HL5FUA

CQing, was

I

busy with a QSO

and missed my

chance

to

respond to him.

Having finished

my QSO,

I

clicked to select

him on the UDP

band map and

watched as my

system

tail-

ended him. He

worked someone else so my system waited then tail-ended him again.

Bingo! It worked! We QSOd!

P a g e |79

FT8 Operating Guide

Logger32 also offers a full-auto “cherry-picking” function – an FT8 automaton or robot – that:

•

Identifies “cherries” i.e. potentially interesting stations on the UDP bandmap, according to the

program’s internal logic and priorities.

•

Looks them up in our log and shows any previously-logged QSO information (e.g. date, time, band,

mode, operator name, QTH, QSL status etc.), plus their country, beam heading etc. as if we had

entered them manually into the logging pane.

•

Looks them up in callsign databases such HamQTH.com or QRZ.com, showing the relevant records.

At the right moment, sends a UDP message telling WSJT-X or JTDX to call them on FT8.

Tracks the sequence of messages to determine whether the station responds to us and completes

the QSO, or else gives up calling after a few goes to wait for the next cherry to ripen.

It’s up to us whether to use the full-auto cherry-picker function at all, and if so how to configure it. As a

traditional DXer (=old fart), I prefer to control my station, only making QSOs while physically present in

the shack, or possibly while at a remote operating position.

If you are excited at the prospect of letting your PC do all the work, robotically driving up your digimode

counts for you, knock yourself out (literally if you wish, subject to your licensing laws about being the

control operator for your station). Just be aware that DXCC rule 6(a) requires “contemporaneous direct

initiation by the operator on both sides of the contact”.

If robot-style full-auto is not for you, or if the

rather cryptic who-to-call-now rules built-in to

Logger32 don’t reflect your DXing priorities,

consider the semi-auto option. Choose your

own cherries: turn off the robot then manually

click callsigns on Logger32’s UDP bandmap, any

of those highlit calls being prime candidates.

Logger32 will then do its level best to prod JTDX

into working the selected stations

Trust me, it pays to keep an eye on things, even if

the robot is running. In particular, make sure your

receive and transmit audio levels remain in the

green. It’s down to you to choose your band and

transmit frequency, to select the best antennas and

turn the beam to exploit useful propagation paths,

and to know when to switch to DXpedition mode or

chase some rare DX that may not be around for

long. DXing takes skills that are hard to automate.

Failing that, ignore Logger32’s suggestions

In addition to practical and technical

constraints, there are design flaws

and bugs in the software.

Sometimes the sequencing fails so

you need to step in and take charge

to rescue or abandon failing QSOs.

entirely: simply double-click the WSJT-X or JTDX decodes from

stations that catch your beady eye to have the programs call

them in the old-fashioned manual form of digital DXing.

Or just CQ and wait for the cherries to fall into your lap – your

lap, your choice.

Watching the robot make QSOs is vaguely interesting at first but Contrary to some naysayers, you

soon becomes dull, compared to the thrill of DXing. Personally, can’t simply wander away and come

I find I can work DX more efficiently and more effectively than back later to collect your awards –

the robot … but the robot wins in terms of chair-time. It can do and anyway, that’s no fun and no

fairly well through sheer persistence. I find it useful, sometimes, achievement for any self-respecting

to unleash but keep a close eye on the robot while I’m busy DXer. You might as well try DXing via

doing other things in the shack such as working … or updating SMS TXT messages or email!

this guide on the adjacent monitor. YMMV.

In due course, I expect there will be (more) calls to outlaw fully-automated amateur stations except for

specific, legitimate purposes such as beacons, Skimmers, propagation pingers and the like. That, in turn,

P a g e |80

FT8 Operating Guide

may stimulate efforts to ‘out’ the robots

The team that invented and released FT8 is adamant

that it should not be fully automated. Fully-automated

operation has some potentially useful applications

such as propagation monitoring and remote sensing,

but for regular DXing most hams agree that full

automation is unnecessary, inappropriate and

unethical, filling the bands with junk, cheating regular

entrants in DX awards and contests, and generally

devaluing the hobby. Frankly, it’s boring and pointless,

not in the spirit of amateur radio.

among us, an interesting challenge in its own

right, the radio amateurs’ version of the

famous Turing test .

For now, full-auto lights-out robotic FT8

stations are fairly easy to spot thanks to

obvious clues such as:

•

Operating 24x7, or at least for extended

periods whereas most normal people

would need or choose to take breaks.

•

Always using auto-sequencing with standard messages – no friendly greetings or off-the-cuff

comments and responses during or at the end of their QSOs, easily confused by out-sequence-of and

custom messages.

•

Static audio frequency for all transmissions – no QSYing to avoid QRM.

Absence from DXpedition fox-n-hounds pileups.

Frank admissions by their operators, or at least evasive or dubious answers if challenged about this.

Stealthier, more sophisticated robots, though, could prove difficult to identify as such and might

conceivably match competent DXers and contesters in capability.

Once the robots can work DX, solve catchpas and write user guides as quirky as this one, my days as a

radio ham and tech author will be over. I can sit on the sidelines watching what remains of my life pass

me by, quietly humming imaginary Morse QSOs with myself, rocking and dribbling.

Be especially wary of leaving the robot operating your station unattended for more than just the odd

moment. Aside from the ethical considerations, practical constraints and bugs, unattended

operation may be prohibited by your license terms and conditions. Furthermore, there are safety

hazards. What if faulty equipment leads to overheating and fire? What if someone wanders into the

shack and fiddles with the controls or touches exposed terminals? What if your system goes haywire,

causing chaos and confusion on air, perhaps QRMing the emergency services? Your reputation will

be shot to pieces and the authorities may come a-knocking at your door.

Fools rush in where

angels fear to tread

[

Alexander Pope]

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FT8 Operating Guide

Appendix H: FT4, a digimode for contesting

In April 2019, Joe Taylor announced FT4, a new digimode specifically designed for “rapid -fire contest

QSOs”. The software and protocol were refined, then WSJT-X v2.1 was released in July with the following

specifications:

•

4 FSK tones spaced ~20 Hz apart instead of 8 tones ~6 Hz apart,

hence FT4 vs. FT8 – the clue is in the name.

Lowest copiable

signal-to-noise ratios

in 2.5 kHz bandwidth

SSB +10ish dB

MSK144 -8 dB

CW -15 dB

•

Small bandwidth (80 Hz) constant-envelope MFSK signals with

Gaussian smoothing (“GFSK”) giving narrow sidebands (pencil

skirts) hence room for more thirsty contesters around each FT4

watering-hole (see next page ►►).

•

~21 baud transmission rate and short overs (just 7½ seconds long

including the couple of seconds needed for decoding) giving quick

QSOs and a max contest run rate of about 100 QSOs per hour, even

without the multi-transmit fox-n-hounds DXpedition approach.

FT4 -17½ dB

FT8 -21 dB

JT4 -23 dB

JT65 -25 dB

JT9 -27 dB

•

Structured messages the same as FT8 using the same encoding

scheme with 77 payload bits and LDPC (174,91).

QRA64 -27 dB

WSPR -31 dB

Reasonable sensitivity, better than legacy modes but 3½ dB worse

than FT8 ►

??

-35 dB*

Overs are synchronized needing system clocks accurate to within

one second (between one second slow and one second fast).

*

Joe & team are

developing a new ultra-

sensitive but very slow

UDP and TCP links to contest logging software such as N1MM+.

mode for VLF experimenters

4

2

For more on FT4, watch these excellent presentations by Joe .

“

FT4 is a special-purpose mode designed for rapid-fire contest QSOs. It serves this purpose

very effectively, but like FT8 the mode is not useful for more extensive conversations. FT4

uses much less bandwidth than RTTY and provides reliable decoding at much lower signal

levels. It has no need for “Super Check Partial” or similar contesting aids, and skilled

operators using FT4 will find less motivation to use a DX Cluster or other non-radio aids. All

information necessary to score well in a contest can be obtained over the air, during the

contest, through one’s own antennas and radios.”

Joe Taylor , April 2019

42

The asynchronous timing approach mentioned in an early seminar was abandoned.

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FT8 Operating Guide

▲

By smoothing the frequency transitions, GFSK significantly reduces the skirts (sidebands)

on the two simulated signals shown on the right of this spectrum plot

narrowing the FT8 bandwidth by a remarkable ~80% at the -80 dB level ▼

Even unsmoothed, FT4 and FT8 sigs are much narrower than RTTY.

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FT8 Operating Guide

That’s it from me,

It’s time for tea.

Go work DX,

I’m QRT!

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